This might just be the best theme for Ubuntu made until now
Numix 2.2, a very modern flat theme that combines a number of dark and light elements, with support for Gnome, Unity, XFCE, and Openbox, is now available for download.The theme has been designed to work with a number of desktop environments, but the Ubuntu 14.04 LTS users have been missing out. Canonical has made some modifications to the window manager in this edition of Ubuntu, and theme designers need to adapt.
Now, the Numix GTK theme has been updated to work with the latest version of Ubuntu 14.04 LTS and it seems to integrate very well with the system. As usual, it’s not enough to just download the theme, you will have to activate it. This means that you also need another application, such as Unity Tweak.
The Numix GTK designers are providing a very simple way of installing the theme, with the help of a PPA. This ensures that users get the latest updates as soon as they become available. All you have to do is to open a terminal and run the following commands (you will also have to be root):
sudo add-apt-repository ppa:numix/ppa
sudo apt-get update
sudo apt-get install numix-gtk-theme
You can also download the Numix 2.2 theme from deviantart.com.