I was very disaapointed with Ubuntu 11.04 release. Even though many people has said that .04 release were always a bad release, i didn't believe that until i saw 11.04. It was really the worst Ubuntu release i have tried so far and i believe many others will have the same opinion as i do. It's like the test case for Canonical to try new features.
Others also said that .10 release is a nice one and based on the report by CRN, they are about to tell us a good news: Ubuntu 11.10 is fast and friendly. Even though it's only Alpha 2 version, it's quite stable, but still not recommended for daily or production usage. You should wait for the final Ubuntu 11.10 which should be released on October 28 if there isn't any major delays.