Dungeon Crawler with no real character progression
It kind of needs to be multiplayer, the match system is kind of handy. The difficultly is strangely easy then ramps way up and additional people are necessary. If you don't have people you end up grinding for gear and that can be tedious quickly. The PvP system sucks pretty hard though. A good patch would fix that.
I like the loot system. Chaining stages together to get better loot is a very good idea, encourages playing. The lack of trading or a way to show off cool stuff is no fun though.
If you like d2 and are waiting for d3, it is a distraction but it won't replace them.