Mictlan is one of the most elegant and carefully designed Gnome-Shell themes and Gtk 3 themes I’ve ever seen. It reminds me of the elegance that you get from the Enlightenment desktop environment, as well as the same persistence to detail and perfection.
Mictlan is compatible with Gnome Shell 3.2 and Gnome Shell 3.4, but for the moment the Gtk3 theme is compatible only with 3.3 and previous versions. Cinnamon and Metacity are also supported.
I’ve been using this theme for quite some time now and I didn’t encounter any weird problems, or bugs I usually find on other themes. Mictlan seems to work perfectly. To give Mictlan a try, you’ll have to download the zip file, unzip it and put the folder in /.themes, open the “Advanced Settings” tool, go to the “theme” tab and choose Mictlan for Gtk theme, Window theme, and for the Shell theme. For all changes to apply, you’ll need to restart Gnome Shell by pressing Alt+F2 and then “r” and Enter. Enjoy!