MadPenguin has made a review of 5.10 Preview, where they also look at some of the things that Ubuntu can improve.
The three-page review starts here.
Enjoy the conclusion!
At the end of the day I don't really give a shit about philosophy or and of the other nonsense associated with the overall Ubuntu image that's being projected. What I do care about is that I have a functional desktop to do my daily work on. Ubuntu has provided this to me in spades during my review period. It's a very impressive distro at this point and I'd recommend it to anyone with at least a little Linux experience who's looking to replace any outdated Linux machines or even legacy Windows machines on their network.
Performance on the desktop was acceptable. I wouldn't say that Ubuntu was a screamer because I'd be lying to you, but it did perform well enough to warrant every day workstation/desktop duty. Applications were quick to respond and overall the system felt pretty snappy. The final version should prove to be quite a performer. This, combined with how easy it is to add/remove/update software (it's Debian after all) will seriously make it hard to beat.
If they continue on down the path they're on now, Dapper Drake (sigh….) will be hard to compete with for the desktop space. This will place Ubuntu squarely in the same league as SUSE, Mandriva, Fedora, Xandros, and Linspire.