I run ubuntu 14.04 on my HP Pavilion 17, but log directly into xmonad running two xmobars, a system that allows me to do whatever I want instinctively and quickly, having slowly evolved my xmonad.hs and xmobar.rcs over a year or so. I've put lubuntu 14.04 on an old HP mini deskbox with an HDMI card for the family media player. My daughter also has Ubuntu 14.04 on her laptop and lives in Unity. Wife and son use netbooks running Ubuntu 12.04. I've revived a good few friends' laptops that were struggling under Windows XP by installing Lubuntu and making them useable again.
I can think of no reason to return to windows.