Technical

Graphics & Performance

• Most if not all of the textures and models in the game appear to have been updated, and look a lot cleaner now that the game is not limited to the PS3's comparatively low texture cache size.
• Less aliasing (read: "jagged edges") on in-game models and geometry (not sure if this is due to the PS4 Pro's 4k upscaling or an anti-aliasing post processing effect.)
• Far fewer loading screens/reduced loading times.

Saves and PSN

• There is an autosave feature to save progress towards Thieves Den rewards; it does not create a new save for you to return to. This progress is retained across playthroughs.
• There is no longer a separate blue "network save" slot.
• You can now take screenshots and video clips up to late December (I haven't tested this yet myself as I haven't gotten that far), after which they are blocked.
• Most (but not all) of the achievements have been updated, and they generally seem to be much less completionistic than the previous game. There are no achievements for ranking up all confidants, getting all vending machine items, clearing all mementos requests, etc. You could probably complete all the achievements in a single playthrough as long as you're paying attention to getting them; I haven't seen any that require a NG+ run.

Sound Effects & Music

• There seem to be quite a few more ambient sound effects that weren't in the base game (like clanking chains/cages in Kamoshida's palace), but I'm mostly playing with headphones now, so I could just be noticing them more.
• There are 20-30 new songs that have been added to the soundtrack.

Gameplay

Story & Cutscenes

• A number of characters that show up later in the game make brief cameos and show up in various places around Tokyo much earlier than they did in the base game.
• Kamoshida can now be seen walking around the school after 4/18 and can be talked to for some more verbal abuse.
• The prologue also has a new in-engine cutscene that introduces Kasumi Yoshizawa.
• On 4/12, there is a new interactive cutscene that introduces the protagonist to Kasumi for the first time during a subway ride to school.
• On 4/18, there is another interactive cutscene with Kasumi and Kawakami.

Daily Life

• There are quite a few new side conversations with NPC's that hint at the new activities and areas added to Tokyo in P5R.
• All of the classroom questions seem to have been changed.
• Bad weather will improve the knowledge gained by studying in the library.
• The tutorial for studying in the library also mentions that you may overhear students talking about you, which will reduce knowledge gained but increase guts. In P5, the description indicated that studying despite the noise would raise guts, I do not know how this has actually been adjusted, if at all.
• "Speed Reader" is a new book available in the library that can reduce the number of times you need to read a book to finish it. It is checked out initially, but will be available on 7/1 near the deadline to Kaneshiro's palace.
• Triple Seven (the convenience store) now pays ¥3500+ instead of ¥2800+, making it now pay more than the flower shop (¥3200+) per shift.
• Rafflesia (the flower shop) now only offers afternoon shifts. Previously you could work there in the afternoons or evenings.
• Working at Triple Seven now also improves your Charm stat.
• Triple Seven now offers a rewards point program that gives extra points on any day of the month with a 7 in it. On these days, more customers will come to the shop, allowing you to earn more Charm points and money than usual.
• There is a new Sports Store in the underground mall that sells some new consumables, accessories, and (presumably) confidant gifts for Ryuji. This store replaces the record label shop.
• A few of the shops in the underground mall now sell male confidant gifts.
• The Shibuya Diner on central street has been renamed to "Bikkuri Boy" and is closed until May.
• The batting cages now offer different activities based on the time of day. At night, you can swing as much as you want, but there are no prizes. Hitting three home runs at night earns you a coupon for a free daytime session.
• Some books now have a prerequisite Knowledge level in order to read them.
• Studying at one of the booths in LeBlanc during bad weather will now increase the amount of knowledge points gained.
• You can use the cleaning tools in the restroom of LeBlanc to improve your Kindness stat during the evenings, and also gain points towards Sojiro's social link.
• You can now sit and reflect on the toilet in LeBlanc, which will give you hints as to how close you are to improving each of your social stats.
• Cleaning up the bookshelf in your room on 4/18 or later will reward you with a few new books to read.
• Cleaning out the rest of your room on 4/18 or later will also give you a CRT TV, although it does not include a tuner so you cannot receive TV blurbs from your room.
• The CRT TV is now replaced with a DVD player at the secondhand shop.
• Scarlet (the DVD rental shop) now requires you to pay a ¥4800 annual membership fee that allows you to rent any DVD you want for an unlimited period of time at no cost. You are only able to have one DVD rented out at a time.
• I believe this was in the previous game, but there is now a tutorial that points out that you can solve crossword puzzles at the far table (near the restroom) at LeBlanc on certain days without causing time to progress.
• You can now explore Yongen-Jaya at night on 4/21 instead of 4/22.
• After exploring the Metaverse, you can now perform activities within LeBlanc and your room, even without Kawakami's confidant bonuses.
• You will now get text messages from part-time jobs on busy days, where you can potentially earn more social points and money.
• On busy days, the convenience store will have a performance challenge much like the Beef Bowl Shop, where you will need to remember barcode locations and then recall them when scanning items.

Palaces

• The prologue sequence at Sae Nijima's casino now has a tutorial sequence that shows the player how to use the grappling hook.
• Individual party members will now occasionally have things to say when in a safe room.
• Morgana gives you a few starter items and infiltration tools when officially infiltrating Kamoshida's palace for the first time after 4/18.
• You can now loot nearby treasure chests and breakable objects while in cover.
• Shadows have new lines of dialog that they will occasionally say when wandering around.
• Treasure chests now make a glittery sound effect to let you know that one is nearby.
• There are new visual and audio effects on safe room doors that make them more obvious.
• Many of the puzzles have been modified and some new ones have been added.
• The grappling hook will now allow you to access new areas in palaces where hidden pathways or treasure might be found.
• Will Seeds are new collectables that can be found in each palace. Finding one will restore a little bit of SP to the party, and finding all three of a palaces Will Seeds will reward the player with a unique accessory.
• With the inclusion of the Will Seeds and grappling hook, a number of areas in each palace have been changed or added.
• Boss fights have a few new sequences and attack animations, but are fairly similar to their counterparts in Persona 5.

Combat

• Guns now replenish all ammo after each fight, the rationale (according to Morgana) is that Shadows will be expecting you to come at them fully loaded. The gun tutorial fight in Kamoshida's palace now has a second encounter to show off this new change.
• Take Over now plays during ambush attacks instead of Last Surprise. Last Surprise will still play during normal encounters and enemy ambushes.
• Baton passes are no longer linked to confidant ranks and can be used as soon as 4/18.
• Performing a baton pass four times in a row will now allow the final party member to use a skill without consuming any SP or HP.
• Enemies in each encounter seem to be much less homogenous than in the base game, possibly to encourage the player to take advantage of baton passes.
• Savage enemies are a new variation of regular enemies that have to be damaged somewhat before the player can perform a Hold Up.
• Disaster Shadows are a new type of enemy that will only counterattack if attacked by the player first. They can also occasionally perform follow-up attacks. Upon death, they will drop an item and explode, damaging any other shadows. The amount of collateral damage that they do is based on the amount of "overflow" damage that is done to them by the player when they die. If they die due to reflected damage or Despair, they will not explode or drop any items.
• Asking a shadow to join you when you already have one of them in your stock now grants extra experience to the persona in your stock.
• Asking a shadow you already have in your stock will usually yeild better rewards. Shadows in your compendium but not in your stock will ask to join you first before giving you money or items.
• Items gained through negotiation vary from enemy to enemy; they have fixed common and rare drops (common being something like a Life Stone, while rare might net you a Balm of Life). These can also be stolen using Joker's Pickpocket ability from Magician Rank 5.

Items & Equipment

• The stats and prices for most (if not all) equipment has been altered at Untouchable. In general, gun accuracy and damage seems to have gone down while prices have gone up (presumably due to the ammo replenishment change). The accessories that are initially available are completely different than in P5.
• Crafting infiltration tools during bad weather will now allow you to make an additional tool.
• The "Stealthanol" infiltration tool has been replaced by "Calming Aroma" which seems to have the same effect (lowers security level).
• The "Element Set" infiltration tool has been broken down into it's four component items (Moltov Cocktail, Freeze Spray, Stun Gun, and Air Cannon)
• Some accessories now have bonus skills attached to them, which can be used by any persona that the player has equipped.
• If you find an item in a chest that is stronger than the one currently equipped on Joker or a party member, they will prompt you to let them equip it automatically.
• The home shopping channel on Sundays now offers bundles of a variety of items, rather than a single item. You will now have to choose between different options. Keep in mind that you can only purchase one and will miss out on the other, so choose carefully!
• All gear that can be washed at the laundromat now is described as "sooty".
• There are quite a few new types of gear, and old gear has been rebalanced as well.

Personas & The Velvet Room

• There is a unique appearance for the Velvet Room loading screens.
• There are quite a few new personas that have been added.
• Some personas have had their arcana changed, and there are now a few new arcana as well.
• After you have officially infiltrated Kamoshida's palace for the first time, you will be able to access Challenge Battles in the Velvet Room by speaking to Justine.
• Challenge battles allow you to earn rewards through battles that focus on specific mechanics like Baton Passes or Technical damage, battles that test your endurance, or battles with persona users from previous games.

Confidants

• Tae Takemi's voice actress has been changed from Kirsten Potter to Abby Trott (who also voices Annette in Fire Emblem: Three Houses, one of my favorite VA's in the game)
• Some of the confidant cutscenes have either had new dialog added, or have been overhauled completely.
• Most of the confidant cutscenes now give more conversation opportunities to gain points towards the next rank-up.
• Some confidant abilities have been altered, replaced, or shuffled around to unlock at different ranks than before.
• Tae Takemi's confidant now has a Guts prerequisite after level 1.

Dialog & UI

• Party members now cycle through three portrait angles (instead of just one in P5) with 2-3 expressions each. The general pattern is head down (sad, angry) head tilted up and back (surprised, happy) and then all of the normal portraits from P5. There don't seem to be any new portraits for non-party confidants or named characters (like Shiho)
• Some of the NPC's are now voiced, like the parcel deliveryman that directs you to Cafe Leblanc when you are attempting to find Sojiro Sakurai's house.
• There are a significant amount of localization fixes for both voice and text dialog as well.
• The dialog indicators (i.e. "whisper whisper" "chatter" etc.) over NPC's that you can listen to or talk to will be grayed-out after interacting with them to let you know that you've already interacted with them.
• Many interactions with confidants that were previously text-only are now voiced.
• Phone conversations now show the portrait of the person you're talking to next to the text box.
• The chat app on Joker's phone now has an animated background effect. (Falling flower petals right now, not sure if it changes as the seasons/weather changes yet)
• Shadows and other entities now have special effects on their dialog boxes when speaking.
• Transition animations when moving between areas have changed due to the reduced loading times. Some of them (like the subway animation) will also change depending on the time of day/weather.
• The glyphs for the Playstation button controls in the tutorial prompts are now colored and shaped like the actual button used instead of being a more generic red-colored character.
• Tutorial pop-ups now allow you to go back-and-forth between sections using the left and right buttons on the d-pad.
• There is now a new "Order Obtained" tab under the inventory interface that sorts items from newest to oldest.
• There is no longer an "Urgent" category of infiltration tools (as of 4/17). These have been grouped into the "Palace" category of tools.
• In addition to sorting by Aracana and Level, you can now sort the Persona Compendium alphabetically.
• The Persona compendium now has a mask icon next to any personas that you already have in your stock.
• There is now a "I need to speak with Igor" option if you accidentally back out of the persona fusion/itemization menu.
• Pressing the touch pad now does more than just showing what other players have done on the same day as you (though that is still an option). It can bring up Assist Commands, which allow you to view recommendations on which confidant you should spend time with, view suggestions for which activities to do, and quickly travel to the hideout with a single button press.
• There are now minimap icons for confidants.
• Confidant abilities that carry over from the previous game now have more descriptive text. (i.e. Ryuji's "Punk Talk" ability now specifies that it only works on upbeat-type shadows.)
• Pressing R2 on a piece of equipment that has a passive ability or modifier will show a more detailed description of said effect.
• There is now a new effect that indicates when a party member has been powered-up by a baton pass. It will change color from red->yellow->blue for each successive pass.
• During combat, there are new status indicators by a shadow's name that show all of their current buffs and debuffs.
• Instead of just auto-healing the group, pressing square while in a palace now gives the player the option to quickly use some common infiltration tools like smokescreens, Goho-M's, and Calming Aromas.
• You can now target specific enemies and points of cover by using the d-pad while hiding.
• Map scrolling speed has been increased significantly.
• Palace maps now have an indicator that keeps track of what Will Seeds you have collected so far.
• The battle summary screen animations have been sped up significantly.
• The animation that plays when going to the next day will be different when sending a calling card.

Miscellaneous QoL

• Aside from the infamous first walk to school, most interactions that involve going somewhere new or following another character will be more guided, preventing the player from getting lost (like when Ryuji shows you the way to the airsoft shop for the first time)

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