it's been 15 years - i switched to the Apple ecosystem w/ the OS X public beta! I had a graphite iMac and a bondi blue powermac tower thing running os9 that i put X on ASAP.
the problems listed at https://gist.github.com/neurobashing/e52a73e7f180902731cb with my apple tv - it's a constant headache
Yosemite has been problematic for me. on 2 out of 3 machines i use regularly, it's basically god-awful. it's not been a good experience for me.
nearly everythign I use every day for work is already x-platform.
the crazy "banned/no j/k you're back" thing of the app store.