I've upgraded both leon (one of my computers at home) and quant (my work machine) to Kubuntu Edgy Eft (now in Release Candidate status, screenshots here). Leon's upgrade went perfectly, while quant gave me some headaches. First of all there was a conflict between packages, then the nvidia module for legacy hardware wouldn't load:

$ modprobe nvidia_legacy

FATAL: Module nv not found.

In the end I manually compiled the nvidia module, and had to insert it via insmod or it would give out a cryptic error message ("error running install for module nvidia"). I think most of the headaches are coming out because I was using a custom kernel and because I dist-upgraded to a still unstable distribution. In any case, I'm quite pleased so far with Edgy, and once it becomes official I'll put it on my laptop as well.