Gameplay has been streamlined, everything moves fast. Menu navigation has been largely improved.
Brings Negotiation back, as well as Guns, and the Nuke and Psy elements. But this does mean that, net-net, there are 10 offensive types you have to cover.
All commu now give useful bonuses at several levels.
The plot is largely a rehash of P4. There's also way too much of "your party members are literally the only decent people in the entire world" sort of morality going on.
Plenty of quality of life improvements.
Lots of the translations are iffy, but just how bad they are have been overblown by weeaboos.
More options to improve social stats, lots of map areas to spend time in, but expect to be railroaded by this fucking cat.
All in all, though, an improvement.