From a Windows user who made the switch.
Updated 10/8/15, 3+ years after the switch
- The green button! I'll never understand the logic behind it. I just want to maximize the application window to fit the screen without entering fullscreen mode, why is it so hard! Fixed with BetterSnapTool. As of El Capitan the default green button functionality is to now make an application run in fullscreen and/or split screen mode and one has to alt-click just to get the prior wonky functionality back.