2. No support for gnome 3
3. Performance in KDE is worse than the OSS drivers. I think it's reasonable to expect windows to minimize without lag on a modern graphics card.
4. Tearing seems to be ever-present. Enabling tear-free desktop introduces microlag which makes watching movies pretty much unbearable.
5. Hardware acceleration for videos is not hassle-free and only works half of the time
6. Wine games lag.
In General, there isn't a satisfactory driver out there for Linux, right now.
Always lacking in some form or another.
At least the AMD and MESA drivers don't suffer from the "Can't disable VDPAU support in flash, so everytime a flash video plays it draws crap all over the screen, everywhere!"