I have found OSX annoying and getting in my way once and only once: Finder. When dragging a folder to copy to another location which already has a folder of the same name... Rather than the sensible approach of combining the folders in the destination, it removes the contents on the destination then writes the source.
Who thought of that should be taken out and shot.
Other than that, the flexibility really reminds me of AmigaOS in some ways. You can have your GUI, but you also can have your all powerful CLI

. The amount of ways of customising the behaviour are astounding as well: the default write stuff is quite mindblowing...
(Use Win7 Ultimate for my HTPC, use Linux daily, and am responsible for microsoft related products at my place of work...)