I have been using Ubuntu for my study and work since 2007. Through all these years, I have been through Ubuntu Desktop which became too slow for my old Dell Inspiron 6400 when version 10.10 was released. I had to switch to Xbuntu , worked very well with some functionality missing in Thunar.

With version 12.04 , I switched back to Ubuntu Desktop to try out Unity on new Toshiba Satellite C640, only complain was Atheros Fast Ethernet card did not work out-of-box, but experience told me there are always hacks available, only you should be smart enough to decide which you should risk applying.