Yes, I'm on a demo rampage this weekend!
1) Dungeon crawling feels fun, slick, and streamlined. There is lots of loot, but the mechanics are transparent enough that it's not too difficult to decide which to junk and which to keep. The skill system is easy to use and the skills themselves are quite fun. A range attack that pierces through enemies *and* rebounds off walls? Yes please.
Between this and Kivi's Underworld there are a lot of good ideas for maximizing the fun in these kinds of games, and I'd recommend playing both for anyone looking to design their own.
2) You get a pet that semi-tanks for you. It has an inventory which you can fill with crap, then send it on its way back to town to sell. Much win.
3) You can duel-wield a ranged and melee weapon, and you will fire/swing with the most appropriate one depending on the range of your target. I had a blast (pun intended) with my hammer in one hand and a pistol in the other.
4) I'm fairly sure the levels are at least semi-randomly generated, which keeps things fresh (that or I have a really bad memory)
1) The cartoony graphics don't do it for me. They are cute if you like that sort of thing though, so WoW players won't see any disadvantage there. For me though it's a waste of an opportunity to create any sort of tension with the atmosphere.
2) There is no multiplayer. They are apparently working right now on making an MMO out of the game and I assume using the single player proceeds to fund this. But, some simple direct connection support circa 1992 would have been much appreciated.
3) The story feels like a direct rip-off of Diablo 1. I mean, they are quick to point out in interviews that "we are the dudes who made Diablo so we are awesome", but you can't just ctrl-c -> ctrl-v the whole thing.
4) One thing that was also plagiarized, which was always quite lame about the Diablo games, was the need to dump multiple skill points in a particular skill, usually for little tangible benefit. Ooh, fear the wrath of my increased 6% weapon DPS! (That's right, they actually use the terminology "DPS" in the tool-tips... that needs to die, stat). I much prefer the other approach where once you have something, that's it, it's yours... a la Dungeons and Dragons, Guild Wars, even Aion.
So in summary, they've got the core dungeon crawling mechanics done very, very solidly. But with no multiplayer and that cartoony look, I just don't find myself wanting to spend much more time with this one.