I'm with you. Diablo 2 is one of my top games ever. We may disagree on Prime 2, but not here. =) I played the hell out of that game. I'm also concerned about the art style. I've heard a lot of people really slamming those of us who don't care for the art direction, and I was pretty miffed with the PC Gamer podcast going on and on about how it's still so early, the art isn't indicative of what the final game will look like, blah blah blah... but that's a load of BS. Art direction is generally decided prior to a lot of art assets even being built, and the fact that things are already so coherent looking and the general art direction seems to be what it is is *very* indicative of this being WoW-influenced. I'm not saying it looks exactly the same, or that a bent in that direction isn't somewhat logical for the company given past successes and wanting to potentially capitalize on a distinctive look which crosses between titles, but it very much smacks of being un-Diablo-ish. We have a jillion fantasy games with brilliant palettes and lots of color saturation, and we don't need another one losing what made its art style distinctive and interesting simply to become just like everything else.
Granted it sounds whiny, but it's a fully justifiable complaint from anyone that's long been a fan of the series. The gameplay looks awesome, the game is undeniably attractive, and I have no doubt that even if you added pink bunnies and unicorns the game would still kick ass and be a great deal of fun to play, but I think even at this early stage the shift in art direction is disappointing and very much something fans should be vocalizing their distaste for. The earlier the better.