I enjoyed what I played of it this past weekend but I fear that there may not be enough depth to keep me coming back like previous Diablo games. No stat point distribution, every player playing a particular class will have the same skills, very few choices as far as how to build your character outside of items, not really a fan of that. I don't see what is going to make me keep coming back, in previous Diablo games you would have several different toons of the same class, trying different builds, etc, with this one it doesn't seem like you'll need more than one toon for each class. Blizzard has been huge on class homogenization in World of Warcraft which is fine because of the type of game it is, but I'm not sure it's going to work in a game like Diablo 3, at least as far as keeping players hooked long term.
In short, loved what I played of it, will thoroughly enjoy the first couple playthroughs, not sure if the depth is there for me to want to fire it up 4-5 years down the road like I did with Diablo 2 - which I played off and on pretty much the entire past decade.