I'm really impressed with the environmental changes we've seen so far (admittedly we haven't seen too much yet). Of course, I also really liked the muted style of the original game. I think it accented the setting very well.
Icewind Dale... It's been too long since I played it to really comment on the art. The mind plays too many tricks on memory to be fully trusted. I'm going with that over the screenshots because - if I remember right - the old games never looked as good in pictures as they did during gameplay.