I use Kubuntu. I've mostly used karmic and Lynx. I'd just recently updated to Meerkat (10.10), had that installed for a month or so before doing the Natty (11.04) udpate. Don't have a lot of time in for Meerkat, and have only booted Natty once I think so far. All that has been used inside of Virtualbox on my PC laptop.
I like it, and I prefer KDE to Gnome. I haven't really ever used Gnome, but on the occasions that for some reason I end up with that on my laptop screen instead of KDE, I don't know my way around it and have to fumble my way through getting KDE back.
I haven't seen Firefox4 come in yet, I'm looking forward to that. I use Eclipse in there, and am trying to set up with FPGA tools to play with Minimig and such things in there. Have been searching for as much free and/or open EDA stuff as I can find, and have the DenX ELDK compiler set up. Also use Eagle PCB a bit in there, though I wish I had known about KiCad before I paid for the pro Eagle license.
KpackageKit is kindof flaky. Use apt-get from commandline or get Synaptic for usual software getting/updating.
