I have now had Karmic Koala installed for about two weeks. I first did the install via 9.04's Update Manager and it was not a very pleasant experience. Perhaps the Ubuntu servers were still being hit hard but the install lasted for more than 7 hours. Ugh! I couldn't quit though since I had no idea what had started and what it would do. So I toughed it out and let it run. Everything worked pretty good except for the video. Screen re-draws were slow and played video almost impossible. I ran it for two days like this until I decided to go ahead and do a clean install. Wow what a difference. Video is sharp and snappy and played video runs as good as it ever has.
Overall I am quite happy with the new install. The boot time is very snappy and faster than 9.04. Watch this video of comparison boot times between Karmic Koala, Jaunty Jackalope, Vista and Windows 7. The test was done on all the same hardware and new installs conducted by the folks a Linux Format.