I can't speak for Windows, but Linux is miles behind OS X in terms of usability in my opinion. The trackpad gestures are fantastic and very intuitive for me to the point where I hate using a crippled trackpad on linux. I can see the appeal of Gnome, which is very simple and intuitive to use. But modern gnome is adopting more and more features of the OS X window management system, like ctrl-tab switching applications rather than windows, the addition of indicator applets, the windows-and-dock overview screen (whatever they call it). From all the complaints I hear I don't think there's anything particularly difficult about OS X file management and window management other than "its different from what I'm used to."