I've had to start using a Windows machine with the company I'm doing some work for this week. In Windows scrolling seems to be the wrong way, and it's taking some getting used to that scrolling occurs on the item with focus rather than where the cursor is currently positioned.
OSX is not all good, but I do find it more intuitive most of the time.
Having used both 'click to focus' and 'focus follows mouse' models under various Unix and Linux variants over the ages, I didn't find that part too hard to adjust to.
I found the scrolling (going the other way) weird... For a while I thought it was ignoring or resetting the preference I'd set on the "Natural scrolling" checkbox. Eventually I realised that it was keeping it, but the relation between what the scroll wheel on my mouse was doing and what the two finger drag on the trackpad was doing was reersed compared to windows. Changing the "Natural Scrolling" setting changed both of these, leaving them still in the opposite relationship to each other than I've come to expect.
That's something I will probably get used to, though, as is the fact that scroll-wheel zoom also works in the opposite direction than I'm used to if I set natural scrolling so that the two-finger drag on the trackpad does wat I want.
At the moment, the biggest annoyance is that the (free) password manager I use on Windows, Linux and Android is not available for MacOS, (although there is a compatible program that will read/write the same file format, but it is a commercial option).
Also, for some reason, the AppStore doesn't like my apple ID. It complains that my apple ID has been disabled (although I can log into other service including the apple ID itself with no problems) and so I can't install anything through the app store at the moment. Apparently, googling around, this means I'm going to have to phone somebody at iTunes support. (The only thing my apple ID has ever been used for is one single purchase of an album for my daughter's iPod nano).