There is a lot to like about Mac GUI. There are also noticeable shortcomings. Mac's menubar, for example, sucks with large and/or multiple displays because the distance between application windows and the menubar can be ridiculously far since only one display can have the menubar and it's always at the top.
My big screen is shared by my MBP and my desktop. Since I use the big screen as my main screen, menubar is shown there and the MBP screen is filled with windows of 'always-on' apps like mail and IM clients. This means menubar for apps displayed on the MBP screen is not only at another screen but another input source. Making the matter worse, the big screen insists on stepping through all five input sources in sequence instead of just toggling back and forth between active input sources. Very annoying.
With Mac, you have to click-to-focus. That sucks with big and/or multiple displays because having lots of screen area means having lots of windows open side-by-side. When I click on something in a window, I expect it to do something more than activate. Because I have to click twice to close a window (once to focus, another to click on the red button) and because I find it annoying to have windowless applications loitering around, I use command-Q more often than window close button. That's nutty.
I am going to stop before my blood pressure gets any higher. This rant wasn't very therapeutic. Rather, it's making me want to recommend Mac to others so they can suffer the same.

Mac is like marriage. It's simply great.