Don't even get me started on iPhone. Putting mp3 ringtone on it is some serious trick coercing of itunes even on Mac. Ios web browser can't even download arbitrary files. You can't mount iphone as a thumbdrive to move files around.
As for mac, magic mouse is basically useless as clicking causes unwanted scrolling especially in adobe apps and google maps. All praise to good people who made Mouse Prefs app and give it away for free. They should get a pot of gold from apple.
Finder is such a piece of crap that basically first advice given to mac users is buy a file manager. It can't display directories above files. You need to install xtra finder for that.
Image browser is nowhere near the functionality of Fast Stone on windows. Also 3rd party browsers are far behind.
Network drive doesn't autoconnect sometimes and often disconnects. Remote folders visible in finder window don't show up in save dialog of a web browser. Folders disappear from favorites in finde for no aparent reason. Finder sometimes doesn't indicate if contents of the remote dir ar still loading so when seeing empty remote dir you don't know if it's empty or it just didn't load yet.
Some high dpi usb mouse can't be used because it feeds mouse move events too fast for mac osx and they swamp mouse down event so dragging a window becomes very hard and deliberate operation.
Dropown menus on finder got damaged after some use. Clicking away from the dropdown menu on some button locks this button, as if it didn't register mouse down event until it gets mouse up event that somehow got swollowed by dissaperaing menu.
Computer sometimes closes very slowly. Finder just hangs and blocks computer restart. Multiple desktops, multiple fullscreen apps, fullscreen apps at all just get in a way. Switching them with gestures is source of additional confusion.
Additional monitors display weird lines when they are turning on an off.
I even installed clean yosemite in hopes that it will fix some obvious defects. It didn't help much.
So far my expeirience with mac that costed three times any of my previous computers is that it's pile of failing crap.
Yosemite is pretty win 98. Maverics was the same but with different skin. Even linux wasn't that bad. At least not for the last 5 years.