Pros: Gorgeous graphics; the pet is a better minion that D3's selection of accompanying NPCs; the soundtrack is smooth and unobtrusive; the quests stack so that you can finish them in any order; you can send your pet back to town to sell extra loot without having to go yourself
Cons: The bosses don't feel as epic as in D3; I'm having a hard time getting the F key spells to work in combat (although this is probably operator error, it does indicate a UI that isn't very intuitive); no in-game help menu (again, it might be there and I can't figure out how to make it work); the world is only one dungeon with multiple levels, where the world of D3 felt more expansive and varied; limited character selection and no customization
Overall: If you like PC/Mac games (as I do), this is a fun way to spend a couple of hours. I don't think it'll hold my attention as long as Diablo III, but neither will I find myself cursing its bugs. It's a gorgeous, well crafted game even if it doesn't seem to have the scale I was hoping for.
And, hey, where else can I spend a few hours running around with a sidekick ferret named Steusselfeld?