So, here's some of my more rational thoughts:
Persona 3 and 4 were both largely about kids 'playing hero'. In Persona 5, it's made more literal by their get ups, which I think feels more self aware?
The way the characters, look, move, animate, dress etc. gives them a distinctly different feel than the P3 and P4 cast. It feels like (at least from this video) a group of characters who know that they're attractive and cool and whatnot, and who think they have an upper hand on the world, and I think it will be interesting if that crashes down. Pride comes before a fall and all that.
Visually, it looks like it takes inspiration from 90s anime like Bebop and Lupin and stuff, but at the same time, it takes a lot from modern design as well. Character's day outfits are really well designed and the characters themselves are all predictably attractive.
It looks like there's going to be a discrepancy between the day art and the night art though, which I think I'm okay with. In the daytime, the cut ins are realistic (to the extent that Persona is realistic), whilst at night they're distorted. The movement of the characters changes also. In the opening video, the characters parkour around a train station pretty realistically, whilst at night the protagonist's movement between cover is cartoonish. Persona 3 and 4 also had a deliberate distinction between the realistic daytime and the surreal other world stuff, and it's interesting that P5 looks to be taking that even further.
I think the trailer has two pieces of music in it. At first, I think the music is the opening song. It syncs up with the video perfectly, right down to the protagonist sticking his hand up as he lands on the train. Then there's a noticeable change in tone, to a presumably different track.
The characters all look older, and more mature. The blonde guy and the blonde girl especially look older than the P4 cast, and the blonde girl's heist outfit is surprisingly sexualised.
Having a cafe as the base of operations is very cool, and very Catherine-esque.
I think I'll need to see more of the night time stuff to make a proper judgement on it. It still seems really weird.