So I finally got this game a couple days ago and it is the first SMT game I've ever played. (never played DDS, Nocturne etc)
I gotta say that this game is super fun to play and very well done. The game mixes the story/fighting/school-life really well and I've become quite engrossed in the world. I haven't been this addicted to an RPG in a fair bit. I wish there was a little more depth to the school aspect and more freedom in your social links, but overall I'm very pleased with the game.
My only one true complaint is the music, which is a mixed bag. Some of it I like and fits well (such as the music during school) but some of it can be a little grating and tiresome. (like that pseudo-rap thing when you're in your dorm) I also think your characters get tired a little too quickly, although in P4 apparently they've taken that out and made it so it's a bit harder to restore SP. (which I think is better and adds more of a strategy element)
I am definitely looking forward to Persona 4. I also hope that a Persona PS3 or 360 game gets made eventually. Not so much for graphics, but with that they take a similar school setting to P3 and expand upon it and add more depth and freedom.
This is honestly the best $25 I've spent in a long time. I think when all is said and done, this well end up in my Top 15 JRPG's of all time, maybe even Top 10. This is also might cause me to track down some of the other PS2 SMT's
To reinforce how much I like this game, it was able to pull me away from playing with EASHL team in NHL 09 which had me hooked really bad.