I completely understand the effort that is going into a project like Diablo 3 and I as well as all other Diablo fans are very grateful for the work Blizzard is putting into creating a truly good sequel.
To make any sort of judgment on Diablo 3 at this point in time would be a very poor judgment at best for even a plebeian such as myself understands that this game is far from being in it's final stages, for art design as well as gameplay.
With that said, I would like to make my opinion heard as to what direction I would like to see the art design go for Diablo 3. From looking at the signatures of the concept artwork, the earliest date I saw was 2004, so quite obviously you all have been working for a long time towards capturing that special look and feel that makes a game a "Diablo Game." I felt that overall, it certainly did capture that uniqueness that is Diablo. However, at times I was thrown off by the look of the background. Rendered as beautifully as it was, the demo was just that, a demo; and although well made, at several points the "look" of the game betrayed the ideas of Diablo, which are: scare the user shitless.
Puns aside, I agree to an extent with most people when they say the art style seems a tad cartoony. The Barbarian looked absolutely fantastic in my opinion! Also the Witchdoctor and his minions looked very good as well. I also have no complaints about the creatures displayed in the game either. But where I do have a complaint is in the backgrounds. I am an illustrator and I know very well that the background can make or break an image. It sets the entire tone of what you are trying to portray. It is very hard for anyone to take a picture of Chuck Norris seriously if he is situated in a field of flowers with beautiful rainbows and unicorns prancing through the happy little brook. Granted, the image would be absolutely hilarious but the artist didn't complement Chuck very well.
I'm more than sure all of Blizzard have higher art degrees than me and my example is simple exaggeration and a weak attempt at humor but what I'm getting at is the backgrounds aren't quite "there" yet. I actually love the color palate and the background graphics are phenomenal (although the leaves and bushes aren't very detailed looking and appear more as a blob of leaves stuck on the ground because of lack of shadowing to create depth). However, the dungeons seemed a little too well lit as well as being a little too "tidy." I'm not one of those guys who want Diablo 3 to be pushed to the edge of black and white, I just would like to see the light radius creep down to a more Diablo 1 likeness as well as have torches and other light sources dimmed as well (or perhaps sharpened to create hard, dramatic shadowing). Through the use of all ranges of lighting, a true air of uncertainty and fear could be created. One of my many art teachers always told me, "It's what you can't see that makes a picture great." What he meant by this was not hide everything in shadow, but partially obscure certain things to cause greater depth or sharper images as well as create emotion and tonality throughout the landscape of the desired image. This likewise goes with having too much detail in that it distracts from the overall image, though you already know that and so far have done a good job in not over-cluttering the game with detail.
Other than those small pointers, everything looks fantastic and I hate you all for now making me wait for Diablo 3 (just kidding). I honestly do appreciate the hard work you all are putting into Diablo 3 and I am waiting at the edge of my seat for any sort of update on the game, be it concept art, features, or even some lies told by someone who says "they know a guy." I have the utmost faith in Blizzard's ability to get it right. They've done it in the past and it's foolish to doubt you guy's won't do it now! My only regret is I'm not employed as a conceptual artist for Blizzard. It would have been a dream come true to do the concept art for my all-time favorite game franchise!
Thank you for your time and all your hard work,