Here are my thoughts on the game:
I like the new skill system. It keeps things fresh by encouraging experimentation, but at the same time you are never caught in a situation where your skill-set is completely useless (like in a boss fight). Overall, the combat is hectic and lots of fun, even more so in coop. The classes themselves are very interesting, though I mainly have experience with the Witch Doctor at this point.
So, now the bad: I can't believe this is the shit plot they came up with after 12 years though I should hardly be surprised after StarCraft II. I know the plot was never a critical part of Diablo games and I wouldn't complain if it weren't for the fact that there is just so much talking in this game. And yeah, 12 years... Don't get me wrong, I enjoyed the early banter between your character and the hirlings, but after Act II I just stopped caring about them because there wasn't anything beyond the yapping. I really wish there were actual side quests for the hirlings.
What annoys me the most is just how happy the game is. I really miss the dread and atmosphere that Diablo 2 had. Everything in Diablo 3 is now bright (in terms of visuals) and comical. Hey, how about a monster that makes farting noises!?? Joy! Characters seem like they are out of Final Fantasy. It just never felt like a Diablo game to me. Don't get me wrong, I liked the locals and the visuals, but I just wish the game was a lot darker, more twisted.
So what now? Well, I know higher difficulty is where the real fun begins so I'm going to try that. Hopefully the intense action can make me forget how horrible the plot is.