As far as I can see, Diablo III reminds me more of the first Diablo than the second one. To some limits of course.
There's no big issues I have with D3. I don't mind the four player limit. I don't agree with the lack of differentiation between members of the same character class. You still choose only a couple of skills from the ones available, and modify each one with runes, giving you lots of possibilities. Of course, you can argue that some are better than others, but I think it will depend not only on the preferences for PvP and PvE but also on playstyle.
The lack of stat requirements on items is the result of not being able to choose stat leveling (the only way for you to 'modify' your stats is with items), so again, no problem there. As far as the no stat choice on leveling, I don't like it, but I can understand it.
The thing I actually don't like, is no open PvP. I find that a major drawback.
Also, on a minor note, so far I don't like the changes with runes they made in the beta. We'll see how it works out.