Diablo3 feels really addicting, like Diablo2. Of course and thats a good thing, in a different way. Personally i wouldnt buy a new version of Diablo2 and i have to admit, im a bit disappointed about some changes in the beta so far. There were actually cool things in the beta and they changed it back to the "Diablo2" feeling. Well thats a personal preference, but in general the game is really cool.
As you already pointed out, the social part is really really bad. The chat is quite small, you havent any cool features like in wow and the guild/clan section wont be released at 15th may version. BN 2.0 feels like an alpha version even after a year of starcraft2. Very disappointing.