First, I am not liking the fact that the game only runs with a persistent internet connection to play on. You should be able to play a single player game Offline, in my humble opinion. Any disruption to Blizzard’s Battle Net means your game is going to take an unplanned break.
The next thing that is bothering me a bit is the new character skill system. While many people would probably disagree with me I actually liked the character building system in Diablo II. In that game you placed a skill point in the skill tree you wanted it and it stayed there forever. This led to planning out every skill point placement way in advance and, also, agonizing about where to stick every one. And that led to specific character builds. If you wanted to try a new build, you created a new character and leveled it. And that led to re-playability.
Under the new system there is no reason to ever create, say, a second Witch Doctor character. Just re-arrange the skills you have. Of course many will say “well, that’s an improvement!” But, in my view it’s not because there is never any joy in starting the game over and seeing how a new build performs from level one. I actually liked that.
These concerns aside, the game is still fast paced and beautifully detailed. Will have more to say after I’ve given it more time.