It has been about a week since I installed Kubuntu 6.06.1 (as documented here), and it has gone pretty well so far, with just a few snags.
One snag was the newly infamous xorg bug that rendered X11 useless on my machine. I still have not upgraded to the newest xorg for fear that it may make X11 unusable again.
A second snag occurred when using KDE's runlevel editor (Control Center -> System Administration -> System Services). It screwed my system up so badly I ended up rebuilding it instead of trying to figure out what it did. Something is a little non-standard about Ubuntu's (and Debian's) runlevel scheme, and doesn't seem to play nicely with the KDE tool.
I updated my installation guide a little bit, to change the default Java installation to use 1.4 instead of sun-java-5. Firefox seemed to lock up frequently on Java sites, so I'm downgrading to 1.4 to see if it is more stable.
So ... a few more snags that I'd have hoped for (I didn't expect to have to rebuild the machine so soon ...), but a positive experience so far. Still enjoying the near-perfect multimedia experience; it is working better than any Linux distro I've ever used in that regard.
By the way, my box-rebuilding was much less painless that it could have been, due to having separate partitions for "/" and "/home". Highly recommended! Just remember to tell the Kubuntu installer not to reformat your /home partition when reinstalling (FYI, my fairly "loaded" Kubuntu box is currently using 3Gb on the root partition, just to give you a ballpark estimate of the space required.)
UPDATE (8/24): Just upgraded xserver-xorg-core and it works fine, even with NVIDIA drivers. Make sure you get at least version 1:1.0.2-0ubuntu10.4
