Guys the difference here is really HUGE!!
Apart from the fact that freezes just disappeared (which were extremely annoying and dangerous for the filesystem), the BIG difference came for me when I ran the 3 Unigine demos.
My system specs: AMD Phenom II X4 B50 (unlocked X2 550)
Sapphire Radeon HD 5850 extreme 1GB DDR5
4 GB DDR3 1333 RAM OCZ Gold 9-9-9-20 1,65Volt
OpenSUSE 11.4 X64 with KDE 4.7.2 Kwin 3D with openGL 2 shaders forced
I saw HEAVEN running at 30 FPS most of the time (and rarely went under it, also three times caught 60 FPS) with Vsync, moderate tessellation, 16X anisotropic, resolution 1440x900 32 bit 60Hz, 4X antialiasing and all of the other options enabled!! Rendering was beautiful with no glitches or artifacts...
With 11,9 Catalyst and earlier HEAVEN was never running with more than 20 FPS (only in 2 scenes managed to reach 30 FPS!!)
The same image showed also with TROPICS and SANCTUARY where I always got 60 FPS and only at one scene in TROPICS counter showed 30 FPS!!
The performance gain I saw is more than double speed and I used Vsync in all of the 3 demos and AMDCCCLE Tearing Free option enabled! I will try to run them without vsync and report back here...
But for the desktop feeling I don't think something changed radically... A slight smoother feeling let's say, it's generally in nice shape here...