More than a year after it came out. ...That game was a delightful mindf*ck. Spoilers ahead.
I really liked it. The plot twisted a lot. I loved how off the opening hours managed to feel, before the Tokyo reveal. I wound up wandering into the neutral ending, which makes me pretty lucky from what I understand, and while it almost ends a little too happily, I was ultimately satisfied (though I'm sad they didn't explain some of the stuff from the other paths, almost like they expect you to get it on a second playthrough, like Hikaru being Lucifer, or the genocide being done by the archangels. That final psuedo-reveal that Burroughs was either the goddess of Tokyo or based on the goddess of Tokyo was pretty awesome, though. Walter and Isabeau were both pretty likable, although I thought Jonathon seemed like a real tool from the very beginning.
The combat was actually pretty fun. The actual gameplay tends to turn me off of a lot of JRPGs, because it's usually so simplistic and so grindy. SMT4 seemed to actually let you compensate for level differences a lot by actually having strategy to your party composition, and to press turns/have buffs and debuffs at the ready.
The combat was growing old on me by the end, and I didn't like that the demon recruiting system was basically just a crapshoot influenced by your luck stat (I much preferred, for example, the card system for getting Personas in Persona 3), but otherwise I enjoyed the game. Requiring all those sidequests to finish the game (on neutral path) really sucked though.
Edit: Oh yeah, really creative designs for a lot of those demons/angels/whatever, especially toward the end. I always appreciate when things opt to go for the otherworldly and unsettling depictions of angels or archangels, and this definitely nailed that.
The music was also really quite good. Did anyone else think that main battle theme sounded like the Buffy theme song?