This is just an improved version of the default GNOME 3 theme called Adwaita.
Reduced the overuse of padding in combo boxes and the primary toolbar(breadcrumb Nautilus bar).
Blended the sidebar colour into the background colour.
Extract the theme to ~/.themes(make one if you don't have it) which will override your root version in /usr/share/themes. Restart with Alt, F2, r.
Only use this with GNOME 3.0, since some of the changes went upstream to GNOME 3.0.x.