Really?
OSX has some very annoying 'features'
Finder - that's the worlds worst GUI ever, must it really be so difficult to go up a folder, can't afford a button for that?
Keybindings - why the hack did they swap ctrl for option - I use 3 machines every day Linux, Windows and OSX and every time I use that damn mac I need to reset my muscle memory for my keyboard. Don't bother mentioning changing the key bindings as I've tried every trick in the book and while it works to some degree it is not applied consistently across all apps so then you have a 'what key do I use in this app' dilemma (which is even worse).
Default dock behaviour is awful. Can't easily see what apps are open, clicking on an icon (terminal for instance) will wizz me to a different workspace and focus all my open terminal instances when I wanted a new instance (yes I know I can right click and select 'New Window', but that's just awkward).
Sure some of these annoyances could be worked around but regardless - by default OSX is a PITA to use in a mixed machine environment. /rant