Weigh-in my experience so far
Given the complaints that I have been reading about Yosemite 10.0.2 I was a bit apprehensive regarding installing it to replace 10.9.5. The first thing I did was create a partition on an external hard drive just so I could try out 10.10.2. I played with Wi-Fi trying to see if there were problems auto connecting to my Wi-Fi network. No such problem occurred for me. Overall, 10.10.2 felt pretty good. I then decided to try it out on my 2011 27" iMac. I always do a clean install of major OS X updates and this install was no different. I find it easier for me to do a clean install as I always put the use accounts on a separate hard drive or separate partition from the OS. When I migrate user accounts, I first rename the user accounts with "_old". When I create a new user I immediately copy the create account over to the separate hard drive/partition and then proceed to manually copy over only the data that is needed. The old account stays around until I am sure it is setup correctly. This could be a week a longer but I eventually delete the old account.
For me this gives me the opportunity to essentially clean out old stuff that is no longer needed. Going to see about not installing flash player. I did need to install Java 6 with the "Java for OS-X 2014-001" for one program. Did verify with Apple if installing it would create a problem as it shows the Lion icon.
Anyhow, so far using 10.10.2 has been great. I even like the flatter look of the graphics. System response seem way better then when I was using 10.9.5. No issues so far with Wi-Fi.
The iMac feels like a new computer again. Next up is my 2009 17' MacBook Pro and 2009 Mac-Mini. I will do test installs, on a separate partition, on those computers first to see how they do with 10.0.2.