I don't want to get into too many specifics or into spoiler territory, but I thought I'd post a quick impression about my time with Diablo III. It's good. No, it's damn good. Not only is it damn good, but I've also been playing a crap ton of it! There's my new rating system and unit of time spent playing right there.
The game is beautiful, it runs great, has wonderful voice acting, the story is quite interesting and the ease of dropping into a coop game with friends is awesome. The not so good includes having to log into a server to play, meaning it's almost a single-player game as long as servers are up, and of course the lag.
The game is so good, and I can be playing for hours and enjoying myself, but it's the little lag or high ping or even the random disconnect that seems to stand out more to me. Always online DRM isn't necessarily a bad thing if done right, just ask Ubisoft about the issues they've had to overcome, my concern is that other companies are going to adopt the same sort of DRM that Blizzard has implemented with Diablo III.
But enough of that nonsense. I am almost to the end of Act II and thus far Diablo III is wonderful.