Ah come on. Yosemite is not a stable, reliable OS? That's just hyperbole...
Running 10.10.3 on half a dozen machines, mostly older ones, and it's stable, reliable and working just fine. MBPro's, Mac Mini's, MBAir, iMac.
Overall OS stability has gone down with Yosemite. I have to restart far more often than I should -- usually after coming out of sleep mode.