My knowledge of postwork tools is pretty limited, but I find the Gimp interface to be so irritating as to render the app worthless. I quickly arrive at the point that I don't care WHAT it's capabilites are; if the interface is such a pain to use, what difference does it make?
No, I'm a believer in UI standards. The GIMP and it's ilk might be cute, but to me, anyway, it's presentation is such a pain to deal with that any potential usefullness is lost in the UI noise.