Hmm.
Couple things as I play more and get into the meat of the game.
Dungeon design - linear but interesting gimmicks. Nothing notable so far. Considering Atlus' penchant for excellent dungeon design, soemthing to look at as the game progresses.
Freedom - complete backstep from P3. In P3 you have multiple cycles through the day. While in 5 you are stuck with really one choice per day. This seems good at first because it makes things more tense. But then the next day you decide to go to the dungeon. In P3 you could prep. After school you have the choice of hanging out with an s link or going to a club or working a job or studying in the library. Right now in P5 I have items I want to sell for sweet cash to build up my compendium. Except I can't because by choosing "let's go to the dungeon today" it automatically goes to the rooftop and I can't do anything else that day. I can't prep and make choices. Combined with the fact that you can only do the dungeon after school and not in the evening like in P3/4 makes the game feels small and limited.
In P3 I made a literal calendar, in real life, for how I wanted to go through a week in that game. I can't do that in P5 and for this reason it's not as addictive. Less sim periods means less choice. The result is what appears to be a smaller, far more guided game. Right now with 12 days left until my deadline the only real choice is to beat the dungeon. Since there's only one real choice, it doesn't feel like a choice. This completely ruins the Persona 3 sim game structure because what makes it so fun is the balance between day (school) and night (dark hour). If you always have to choose between dungeoning and school, there is no balance and if there is no balance then the game loses its unique game structure and gameplay loop. Awful design.
Battles - very boring so far for a Megaten vet. So far the only silver lining is that sp healing items feel limited so I can't just beat the entire dungeon in one day.
Story and characters are great but the gameplay...I just don't know. Still fun, but it just feel limited to me. What were they thinking making you choose between doing the dungeon and studying/doing a part time job/s links? Bad design choice.