My problem with CCC is that it won't run. Period. Since about Catalyst 5.7 I think...
When CCC was first released, I tried it and it ran fine... but after a couple of driver updates, it refused to run for some reason. Even after a fresh load of Windows and all the updates, I still can't get CCC to run with the latest drivers. It's extremely odd and somewhat annoying... but I don't mind sticking with the Control Panel. I just wish I knew what the problem with CCC was.
(Running a Radeon 9700Pro, in case you're wondering)