What was impressive for me in gnome3 and unity was the huge move away from Windows happening in mainstream distribution defaults. It looks to me like we are still in good place of trying out other peoples ideas without copying their products.
With Windows 8, even Microsoft itself is moving away from the traditional Windows interface. So I'm not sure whether Gnome and Unity are actually being creative in departing from Windows-like interfaces, or merely following the latest trend. The trend used to be led by Microsoft, and the Linux Desktop followed it at the time. Now the trend is led by Apple, and the Linux Desktop follows it again.
The OS X shell hasn't changed terribly much since it was first released. GNOME Shell ("GNOME 3") was publicly designed prior to anyone seeing Windows 8 or Unity (in fact, Unity started after the GNOME 3 development process began).
GNOME has more in common with webOS than OS X, Windows 8, or (perish the thought) Unity.
