A lot of people like the Faenza icon theme but for me it just didn't feel right because I just can't give up the Elementary GTK theme. But John Green created created a theme called Faenza-Cupertino which only replaces the original folders to make it look more like the original Elementary style, but using the Faenza icons.
To use it, you'll need the Faenza icons which you can install in Ubuntu using the following commands:
sudo add-apt-repository ppa:tiheum/equinox sudo apt-get update sudo apt-get install faenza-icon-theme
And then download and install Faenza-Cupertino.
[Thanks to Ubuntu Life!]