This probably has close to the most spins out of any ps2 game I have; it's a rare co-op RPG gem with a great story.
You start the game by being able to play online or with a friend, or by yourself...and its an over the head RPG.
That alone should get you excited.
Once you name your character you get started whoopin' some butt.
The game is both challenging and rewarding with a decent enough leveling system and the classes are different enough to make you want to play them all; and if you do the game will feel much different.
Easily, the best part of the game is co-op. Taking the hordes on with a friend (or your wife) is lots of fun. It's an accessible enough leveling system where wives and girlfriends can jump in without much of a learning curve even if they are not big RPG dorks.
Because of this the replay value is absoltuley through the roof - think Diablo for two players on your console.
The graphics are well enough and the storyline is servicable. The game's voiceovers, etc could be a bit better, and the cutsceens are a bit simplistic but I'm being pretty picky here.
This is easily one of the best games I've ever played, and the amount of hours I've logged on it is scary. I'd reccommend this game to anyone.