Yosemite has been nothing by problems for me
I have been a long time Mac OS X user since the Tiger release, and I have to say Yosemite has given me nothing but problems. The reason I originally moved to Mac OS X was because back in the days it was better then Windows XP, and Mac OS X was better then dealing with all the Linux X-Windows hacking. It seemed to me to be a dream Linux/Unix Desktop. But now with Yosemite I have changed my tune.
I have a Mac Pro 2006 running Snow Leopard and it has been rock solid (can runs months at a time without any crashes or issues). Snow Leopard seems to have been the last quality desktop OS release from Apple. I am glad my Mac Pro 2006 didn't support anything past Snow Leopard (due to not having a 64 bit EFI). I was using that computer until recently when I moved to using 2 MacBook Pro's (a 2012-mid, and 2013-late).
First issue I ran into running Mavericks was when I plugged a external high-resolution Apple Display into the 2012 it would randomly just mess up, sometimes requiring me to reboot to get it to come back up. I looked into everything and couldn't find a fix. I then ran into a iCal bug in Mavericks (which took me a long time to find). I decided to upgrade to Yosemite to see if it would fix those bugs. It did fix the iCal bug, the display issue continued. I then tried with a different display and it still had the issue, but instead of the display crashing it would just randomly drop signal to the monitor. Took to the Apple store and they replaced the logic board, but that still didn't fix. In addition to this issue, Yosemite has introduced a bunch of issues I didn't have in Mavericks. The whole OS will randomly completely crash (on both my Macbook Pros), which I have been reporting to Apple. Sometimes when I move to another screen, all the desktop icons are gone. If I move off that screen and back to it they appear. Sometimes I have messed up artifacts in the display (even took video of it), which requires a reboot to get rid of them. Not only do these issues happen on one Macbook, but both (except the external display issue only happens on the 2012 Macbook).
So finally frustrated and running out of ideas, I had one last test. One the Macbook 2012 I installed Windows 7 dual boot using Bootcamp. Since using Windows 7 I have encountered "zero" issues. The display issue I was having is gone. I even have to admit the system GUI response even feels faster running in Windows 7. It just feels more snappy overall. This is even after I installed the exact apps, and based my usage exactly to the way I used the Mac install.
So I have decided Mac OS X has become worst then Windows, even running on their own hardware. I am looking forward to Windows 10, and will probably consider giving Microsoft a second look after all the issues I have had with my Apple hardware recently (the exceptions being my AppleTV and Mac Pro 2006 system running Snow Leopard). I mostly blame this on when Apple increased their release schedule. Releasing a new major OS version every year is too fast, and their quality has went downhill since, at least in my experience. To anyone not having issues, feel lucky, and I wish I was you. The fact some of the issues appear on 2 different systems, and when 1 system got Windows 7 installed it worked flawless, tells me Mac OS X has some quality issues. I hope the rumors are true and the next release concentrate more on stability then features, like the release Snow Leopard was. For me all the OS releases after Snow Leopard have added more bugs then features I actually needed. If all the new software supported Snow Leopard, I would probably just continue to use that on all my Macs.