Having just upgraded to Ubuntu 8.10 my key observation is that it's important to read the release notes first.
http://www.ubuntu.com/getubuntu/releasenotes/810 [1]
There are a few bugs which have affected me
On the plus side KDE 4.1 is looking very pretty, and the move to subversion 1.5 will be very useful in the long run.
I had hoped to get my 3G connection working as a previous update seems to have broken it - but so far still no joy.
update:
There's a solution for the Kubuntu Intrepid Dual Monitor Blinking
issue here: http://blog.nixternal.com/2008.10.22/kubuntu-intrepid-dual-monitor-blink... [2]
Links:
[1] http://www.ubuntu.com/getubuntu/releasenotes/810
[2] http://blog.nixternal.com/2008.10.22/kubuntu-intrepid-dual-monitor-blinking/