I'm a big fan of Witcher but I don't think it looks better than Skyrim.
I like the art direction that Skyrim is taking as appeals to me more than the Witcher's. However, I feel that the Witcher does have better graphics.
As for the topic, I appreciate the work done by the developers. The game does looking visually stunning with all the overwhelming vistas. Although, I feel that the leaves could look a tad bit better and same goes for the facial animations too. All-in-all though, I satisfied with what I've seen in the trailer.
On a side note, I was wondering whether the cities will be open, since I don't particularly see any walls erected around these buildings - http://oi54.tinypic.com/14vmob7.jpg and http://oi52.tinypic.com/2vcauy9.jpg. I could be wrong though.