MTV Multiplayer has an article about how some Diablo III fans are not happy with the art direction of the new game. And yes, I was surprised too that MTV had a gaming website!
The common complaint seems that the game looks to bright, that it looks like World of Warcraft. Personally I think that all the edited screenshots look like crap, D3 looks great the way it is. The article is a good read, has screenshots for comparison along with an interview with a few of the artist that are working on the game. Check it out here.