Finally got around to trying it last night.
I think it looks very, very good. I didn't have any existing saves, so I only got to check out the area around Xardas' Tower and Lobart's Farm.
Performance is a little rough for me, but I noticed that even the vanilla game was somewhat sluggish for me in Win7 64. I think there's something wrong with my installation.
I noticed some minor flickering in the sky sometimes, although I think it was only at night. I also found myself getting stuck against the branches of some of the newer trees in heavily foliated areas. This happened a lot in the valley where Lester is.
Originally Posted by JonNik 
Off Topic: Anyone have any problem with the game and mouse control?
No issues with my Logitech Performance MX, but the camera certainly takes some getting used to after playing Gothic 3 lately. Something about the way the camera pans in Gothic 1&2 always makes me feel slightly disoriented and even a little nauseous if I haven't played them in awhile.