Here's some screenies if you don't wanna watch the trailer.
Here we see our protagonist walking through what appears to be a train station. Look in his backpack. It's.... a cat! Sound familiar? It appears that it's just a regular cat.... until..
It turns out to be a little like Teddie! Her name is Morgana, the shapeshifting cat burglar. She has some connections to the 7 deadly sins.
The blonde haired boy is Ryuji Sakomoto, not to be confused with Ryoji from Persona 3. He looks like the Junpei/Yosuke/Ekichki of this game. The girl's name isn't completely confirmed, it's either Anne or Anzu, but I prefer Anne, personally.
The Protag sleeping in class, which was a thing in P3/4. A few seconds later, he gets hit with a chalk! WELP~
We see that the protag isn't as mild-mannered as he appears! He does some really cool and fast sneaking around, so perhaps there is some sorta stealth part of the game?
The Protagonist on the top picture, right above his Persona, Arsene! This seems to be taking a Lupin-like inspiration!
This shot reminds me a lot of Persona 3, where you randomly get those comic book-like shots coming in when someone is happy/surprised/angry. It looks pretty cool!
This looks like a cutscene, but then you see the health bars at the bottom of the screen, so I'm guessing it's actual gameplay, which I think looks pretty cool.
A shot of battle, the protag being in the front with Anne/Anzu in the red. It appears everyone will be using a type of gun, with the exception of Ted- I mean Morgana, who uses a screenshot. I believe they will also have a melee weapon; however, I'm not entirely sure!
Some shots of platforming in dungeons, which I'm guessing means bye-bye randomized floors.
People originally assumed this was the protag turning into his Persona; however, we have seen them separated. Perhaps shadows make a return?
DEM MENUS, MAN
Also, notice that there are no Social Links. I REAALLY hope that Cooperation is just a new name for it, because I love the Social Links in 3/4.
The little face cut in that usually happens during a critical/weak attack.
I'll post more if I find them.