I occasionally had some suspend/resume problems, but I seem to have had the same ones on Windows OEM install I used to have and on the new "not so legit" one, so I can't blame Catalyst(not the Linux version at least, if both Windows and Linux have it xD ..).
If this helps you ..
I haven't had as much of a bad experience with Catalyst as I'd expect from what I've heard .. But certainly not as good as it could be or what I hear it could be from others with NVIDIA(my limited testing on my older NVIDIA laptop agrees ...). And I did need a couple tweaks to use correct power management and have low temps .. But now it's probably better than on the default Windows install there was ..
I didn't have the best experience with the open driver .. Mostly power management(and overheating ..) .. But at least didn't have some glitches that I had with Catalyst(no lags on Gnome Shell or excessive CPU usage and overheating, which was fixed in Catalyst 12.6 I think, but cairo-dock still flickers and stuff on OpenGL mode with Catalyst .. xD )
Actually instead of straight Ubuntu I had installed Ultimate Edition 3.4, but it's basically Ubuntu 12.04 with a ton of ppa's, programs, themes and tweaks .. And I pretty much reverted it to basic Ubuntu and purged most ppa's(later added my own though ..) at some point(didn't want to reinstall ..). I've done some testing on others though as well.
That's pretty much my feedback with Catalyst. I've used it on Arch Linux(at the state updates were January to July), Ubuntu( 12.04 ), Chakra ( updated from July onwards ), Fedora ( 17 ) and probably a couple other I forgot already ... But I should say that only on Ubuntu I could get power usage to be how it should be.
And KDE is pretty nice, the most complete DE in my opinion (just uses 100-200 megs more ram than some lighter ones and starts a bit slower.. no flaw I can find othen than that). Don't shun it like that .. :P