This should definitely be one of the default themes in a future edition of Ubuntu
Faience, a very smooth and beautiful GTK3 theme for the GNOME 3.6 desktop environment, has reached version 0.5.3.Faience is still a work in progress, but it also contains GTK2, Metacity and Gnome-Shell themes, not to mention an icon theme based on Faenza.
As a side note from the developer, it only provides support for Gnome 3.6 and it needs Murrine (GTK2) and Unico (GT3) engines to work properly.
Highlights of Faience 0.5.3:
• New Faience-Ocre (for Gnome-Shell), Faience-Claire (for Unity) GTK2, GTK3 and metacity themes have been added;
• The background color of Nautilus canvas items, when the right-click menu is displayed, has been fixed;
• Buttons now have animations for GTK3;
• The overall look of Gnome Documents has been improved;
• Assets have been updated in order to better match the GTK3 widgets.
The installation is done through a PPA. Just enter the following commands in a terminal and then use Ubuntu Tweak to set the theme.
sudo add-apt-repository ppa:tiheum/equinox
sudo apt-get update && sudo apt-get install faience-theme faience-icon-theme
Download Faience 0.5.3 right now from Softpedia. Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.