So far the only big annoyance with Snow Leopard, well Quicktime X at least, is for some reason it will only play some of my ripped DVDs (mpeg4) in 4:3 
The resolution of the movie is indeed 4:3, but Quicktime 7 correctly stretched it to 16:9 or there abouts where as Quicktime X seems to ignore whatever option Handbrake used when i ripped my DVDs.
Oh, and if I go full screen with Quicktime X and hit the stretch button it tries to be clever, the stretch isn't linear, the middle third doesn't get stretched, only the edges...
The resolution of the movie is indeed 4:3, but Quicktime 7 correctly stretched it to 16:9 or there abouts where as Quicktime X seems to ignore whatever option Handbrake used when i ripped my DVDs.
Oh, and if I go full screen with Quicktime X and hit the stretch button it tries to be clever, the stretch isn't linear, the middle third doesn't get stretched, only the edges...