The thing that confuses me the most about it is when I close the last window of an app, 95% of the screen shows the app beneath it but the menus are still for the app I just closed. I guess that's partly a crossover with the focus model as well, but it's just a bit alien to me. As you say, it's really a non-Mac user thing; I only use OSX 5% of the time at work so never really get used to it.