Uncheck or tweak the simplify parameter. This parameter overrides the subsurf level of every object in the scene.

When opening the file, make sure "Trusted source" is checked. Otherwise the rig scripts and drivers dependencies won't run, and will make the whole thing unusable (exploded mesh, very slow...) Go to  User Preferences (Ctrl-Alt-U) -> File -> Auto Run Pythons Scripts to set it enabled by default.