If you’re not a big fan of Unity or Gnome 3 and use KDE with your Ubuntu Linux (or, Kubuntu), you may want to try KDE 4.9 which was recently released.
Ubuntu 12.04 comes with KDE 4.8.4, so if you’d like to try KDE 4.9, run the below commands:
sudo apt-add-repository ppa:kubuntu-ppa/backports -y
sudo apt-get update
sudo apt-get upgrade
After fetching about 500 MB of archives, log out and log in again (or, simply reboot) and enjoy KDE 4.9!