Actually I've found the gimp to be rather useless on all counts. While it can open psd files, it doesn't support all the filters that photoshop does, so if the author of the file did anything fancy, it won't show up.
I give all respect in the world to gimp users, but I've seen sample artwork done in gimp and similar aw done in photoshop and the differences are clear.
Getting back to the "topic":
I'd say photoshop is better than a dry hump with a fat chick, not because it sucks, but becuase I don't love photo manipulation THAT much.
