Karmic? Got it, works great with minor issues.
I'm running Kubuntu Karmic, and I upgraded in place from Kubuntu Jaunty, I did not do a fresh install.
Seems to work better with ATI drivers, I've got the proprietary driver working for the first time since I bought this A780GM integrated motherboard. Nice to see the good old spinning cube desktop change running here again.
I'm happier with it than I was with Jaunty.
Minor rough edges. Workarounds mentioned not guaranteed to work for everyone.
1. USB ports after hub not recognized. Workaround - unplug, replug, enjoy your peripherals.
2. Suspend (pm-suspend - mine is set up with uswsusp) only works when you push power button, not from keyboard. Since it works on wake-on-LAN, it would be nice to see it fixed, but I'm in no hurry. However, if you want this to work consistently, you need to find a place to put (as root) ethtool -s eth0 wol g - best way to do that is to add it as a pm-suspend quirk so it'll get run during machine shutdown.
3. Sun Virtualbox does not print from WinXP with Kubuntu Karmic host. Presumably, you've already enabled yourself as a member of the vboxusers group. Add yourself to the lp group as well.
4. Network management applet still does not work properly. This may be because I manually edited a few files to deal with the same problem in Jaunty.
5. Proprietary driver manager (access via Hardware Drivers from menu) does nothing when you click activate button. Workaround - install envy-ng from repository and run it, if it won't run from the menus, use sudo envyng-t from terminal to run in text mode ... and it's easy once you do this.
Presumably, people who adopt Karmic a few weeks from now will find all or most of these problems solved out of the box.
No horror story, no drama. Just another routine upgrade that leaves things running better and looking cooler. Oddly enough, I'd been having serious trouble with Debian since Squeeze (DRIVERS!!!), I did a fresh install to Kubuntu Jaunty a few weeks ago in the hopes that Kubuntu would deal with driver issues better. It does.