I use Kubuntu on my Thinkpad Z61t and I have been pretty satisfied with it. I've hit a strange snag recently though. Sometimes the keyboard would do wierd things as if the keyboard layout has changed or CAPS LOCK had been pressed which as you can imagine is quite annoying :)
So, the other day they released the Kubuntu Feisty Fawn Beta and since I've heard good things about it, I thought why not? They wanted people to test the new Distribution Upgrade tool so of course I tried upgrading my system that way. A couple of notes about my system as it looked before the upgrade: My system was a Dapper install that was later upgraded to Edgy. That upgrade didn't go too well and required quite a few fixes before I had a working system again. Of course, a large part of the reason was my own fault because of various modifications I had made which the upgrade can't always handle too well. Also I have installed various other stuff - I've upgraded to the latest releases of various software like KDE itself, Amarok, Digikam and more. All in all, it is far from a standard Kubuntu Edgy install.
Considering the above, the upgrade tool did a quite good job I think, but it is not ready for release in my opinion. I'm confused about who it is meant for? If it is advanced users, then I don't really see the need for a gui tool. If it is meant for novice users, then it asks way too many questions. I'm far from a Linux expert but I have used it for some time now as a desktop so I think I know a bit, however I was surprised to get a lot of x.org configuration questions, some of which I couldn't answer (what kind of mouse is attached to your computer? it's a laptop and I don't have a mouse attached...). Why do it need to configure x.org? My laptop have Intel graphics with nice open source drivers, why can't it just used the current configuration that has worked nicely until now? Of course, it might be a broken x.org configuration that was the reason for the wierd keyboard behaviour.
In the end (almost at the end of the upgrade) the tool failed with a dpkg error and stalled. All I could do was to reboot. After rebooting I was greeted with a surprisingly well working system. I had expected a system that was more broken than after my previous install.
I played around a bit with it and I didn't find anything particularly wrong with it, but I still had that strange feeling of using an old system with a lot of cruft (I can't really explain it better than that), so I decided to do a fresh install (there's just something nice about a fresh install). The install went just as well as I expected. The only thing I'm not quite satisfied with is the way it handles partitioning. I wish I could come with a clear comment on what is wrong with it, but I can't, sorry. I just know that I've used better tools. Other than that, I'm impressed. You just answer a few questions about where you live and what language you want to use and that's it, you blink and Kubuntu is installed. Seriously, the install finished much faster than I expected - a nice surprise.
How do I like Feisty Fawn so far? I like it a lot I must say. I haven't really used it much yet, but I have tried a few things. I thought I would check whether the automatic install of proprietary stuff worked. First thing I did was go to YouTube to see if it would automatically install Macromedia Flash 9 for me but that didn't work for some reason. However, a friend then posted a link (can't remember which one) which I visited and apparently that needed flash and up popped a dialog asking whether I wanted to install flash! I clicked OK and it installed and I can now play flash movies on YouTube :)
I also tried playing a DivX video in Kaffeine which didn't work either so I launched the application installer and found a codec pack, installed it and it worked :)
Yes, I know proprietary codecs are bad and I hate them just as much as everyone else (I'm a huge supporter of free, open standards and hope software patents didn't exist!), but they are difficult to avoid, at least they are for me and then it is nice that it is easy to install them!
To sum it all up: I'm pretty happy with my new Kubuntu beta install - notice I haven't mentioned any crashes in the new install? That's because it's been rock solid so far - quite impressive from a beta release I think ;)