I like mythology, so it's fun know a little more about the demons. They are enough hilarious many times and it's something it have roots on the original games, so, even I don't played Megami Tensei games since its inception, I have played a lot of them, so some way I'm kinda charmed with interact with demons.
One of my favorite instances of this is ironically on P1 & P2 (where I really dislike the negotiation system), where a Persona and a demon (or group of them) interact each other and they talk some cool stuff. It's easier on P2, but on P1 I only got a chat between my Persona Lilim and the demon Lilim. Man, now I am replaying Devil Survivor 2 Record Breaker I would love if in the game there is some kind of negotiation system. Just for the old times.
Persona have the luck (and the compromise, 'cause Atlus definitely is going to reuse the assests on future titles and such) to get back the negotiation system.