I actually like what they've done with Diablo 3. I think it's the only series Blizzard hasn't ****ed up yet.
Yes, the gameplay has been "simplified" but it's more like it's been streamlined. You don't get to pick your stats or your skill progression, but considering that you had little choice in stats in D2 (i.e. there is definitively a RIGHT and a WRONG build) and the skill progression in D2 forced you to be stuck with the same group of skills for a long time, the change to a variety of interchangeable abilities is actually rather fresh. Even the shift to weapon-damage-determines-skill-damage makes a lot of sense from a balancing standpoint. All-in-all, the improvements outweigh the increase in simplicity.
The graphics, while "simple", are crisp and run well on any modern machine. The texture work is, as always, top-notch and the art direction is perfect. Yeah, it looks "cartoonish" from a certain point of view, but only if the cartoon is a grimdark gritfest wherein everybody dies by being ripped apart from the inside by parasitic worms.