Bashiok addressed a couple of visual in the forums. The first query was a long one about the isometric view that basically boiled down to “will we see reflections in the game.” Bashiok says yes.
Specifically for reflections though, yeah, we have those. The small puddles in Tristram for example reflect a cloudy sky and full moon.
Elsewhere, a fan asked how higher resolutions would be handled in Diablo 3. Short answer; you’ll see in more detail, but will not see more of the screen (except widescreen). Here’s Bashiok’s full reply:
So, personally, I think a widescreen monitor would be a good investment. For a lot of reasons/games really. But for Diablo III a 30” 16:10 isn’t going to let you see more of the environment versus, say, a 19” 16:10. You’d just have the visual quality improvements that generally come with a higher resolution.