First things first, this game is insanely hard. you die. you die a lot. But it's also insanely addicting, and every time you die, you do it mainly because you made a mistake, and you know it! so you try again...and again... and again... until you master it and move to the next series of deaths.
The foes are challenging but predictable; as are the Bosses. the loot mechanic is fairly standard in the genre and the equipment mechanic is slightly unique, with the ability to upgrade armor and weapons and apply certain properties. all in all intuitive and fun to play.
If you're looking for a game that is all about patience, skill, pattern recognition and good timing with a bit of luck and ALL challenge, you MUST play this game. Expect to be frustrated. It's not your standard RPG where you can hack and slash your way through.
The multiplayer aspect is ingenious... Being able to share messages and watch other players' phantoms pass by you is impressive... and then you learn you can summon them, be invaded by them and even invade theirs!
Its well worth the time, and well worth the money. Just make sure you schedule breaks or you'll find yourself losing the feeling in your legs when you realize its 3am and jump up!