[GeronL]

does it look substantially different from Windows? I've seen some Linux screenshots and was actually impressed, especially by the 'image editor' named, oddly, GIMP

If I ever go Linux, I'll definitely want that.

screenshots?

[Swordmaker]

From Apple's site:

Directory or Folder window:

Changing users:

[antiRepublicrat]

does it look substantially different from Windows?

It's what Microsoft was lamely trying to make Windows XP look like.

I've seen some Linux screenshots and was actually impressed, especially by the 'image editor' named, oddly, GIMP

OS X is not Linux. It is an advanced user interface sitting on top of BSD Unix. You may be able to recompile GIMP for it though, I'm not sure.