The things I have noticed so far:
The obvious ones like a few new icons, different swipe to unlock and answer calls, etc. that people have mentioned.
I'm using Zeam Launcher and the two things that annoy me so far are:
1) No more wallpaper scrolling as you swipe screens, and
2) When I change a wallpaper the crop box is now rather narrow from side-to-side. It cover the whole height top-to-bottom, but I can't make it bigger or smaller from side-to-side. I can move the whole box from right to left, but not expand it or shrink it.
Also, the wallpaper looks larger, not well framed, and almost like it is in a lower resolution.
When I switch back to TouchWiz, I still get the smaller crop box, but the wallpaper ends up looking just fine from a resolution and size standpoint.
Tested it in ADW Launcher and ADW EX, and had the same problem as in Zeam. Don't know what the problem is but I am not particularly pleased with this part of the update.