I can understand that for you this may be true, and for everyone out there that has not experienced major Yosemite issues, I'm glad that you don't have the same problems. But in reality that doesn't invalidate the many people who are experiencing slowness and other issues.
I have 5 machines that I have consistently seen issues on. 2 of those machines were wiped clean and had Yosemite installed fresh. All have had permissions repaired, etc... yet exhibit similar slowness and bugs.
If I only had one or two machines experiencing the same issues then I could say that it was an oddity or the machine(s) had problems. Or even if if all 5 machines were setup the same, same model, same software, etc... then I could say it had something to do with a particular setup or hardware. But the reality is, these are 5 different machines, different hardware specs, different software combinations, all with different uses so I would guess the issue is a broader issue at hand.