So I'm like 8 hours in and I must say that this game is really well made. It doesn't fall under the MMORPG line since it handles co-op maturely; as in, co-op has detriments as well as benefits. If you die, you turn into a soul, meaning you don't have your body. It's possible to request to join other games and cooperatively defeat bosses in order to regain your body back, but you won't defeat the boss as it's done in someone else's game. If you have your body, and summon souls (real players that have died) to help you defeat a boss or level, and the boss is defeated, you clear the boss and they get their bodies back, and are sent back to their own world.
The game is hard. Really hard. You're going to die, and you're going to die a lot. You can't even level up until you've defeated the first boss, then things start opening up. Levelling isn't traditional, it's more like you need to level up in increments of souls. For example, 500 for one level up, then 1000 for the next, then 2000. Levelling goes by stat, not by overall level, sort of like Super Robot Taisen (that's the only other game I can think of that's also an RPG and also has this system).
So yeah, if you have a PS3, I would recommend checking it out if you 1) like difficult games, 2) want to play a wRPG or 3) want something similar to Monster Hunter.