IMHO the best reason is faster boot and perhaps LTS. -Ubuntu One is nice, but not a must. -The new Light theme is just the default theme and it can be changed,

IMHO the best reason is faster boot and perhaps LTS. -Ubuntu One is nice, but not a must. -The new Light theme is just the default theme and it can be changed, so not a reason to upgrade. -The inclusion of Quickly and Acire on the repositories is fine if you're programming with Python... -I'm not that into FB, Twitter, etc so that's not a plus for me -I see KDE as bloated, I do prefer something more lightweight like Lxde or Xfce