Yesterday I upgraded my two old Ubuntu PCs to 9.04. So far I'm liking 9.04 as it boots faster than 8.10 did and it's a more polished layout. Now if only Google would release the Linux version of Google Chrome with the same speed boost over the other browsers like it has in Windows. When Chrome arrives, then these Ubuntu boxes ought to be pretty peppy!
UPDATE 6/6/09
I just installed the developer release for Chrome for Linux and am using it now!
It's not the super-fast browser that the Windows version is (at least on this machine), but it's nice to see it ported over. Here's the link:
http://dev.chromium.org/getting-involved/dev-channel