I've had quite a lot of issues with Mavericks, though.
Yosemite solved them almost completely.
Almost, because sometimes my 2012 MacMini will randomly disconnect from the WiFi access point (an almost 10 year old Linksys 54MBit AP-only).
Then, I have to disabled WiFi completely, wait a few moments, re-enable it and reconnect to my AP again.
It's very random, which leads me to the conclusion that it could also be an issue with the AP and/or all the wireless networks around me, probably using much later and much "better" technology and basically killing my WiFi.
I don't really blame Apple. There are so many devices out there, so many buggy firmware- and driver-versions, so many buggy OSs and the spectrum is so overloaded these days as everybody and his dog has at least one WiFi AP (sometimes several, via a mesh-setup or a simple repeater (adding to the problem inadvertently...). I sometimes wonder why works at all.