Yeah, what is up with the QA? Who do they think they are? Compaq?
Compaq before HP would at least put a check on a circuit board and retire the board after so many deploys to the field. This is concerning because they had this on those boards at all. I'd like to at least have the illusion that was repairing with like-new parts when I was still working on those things. Now that I think of it I should have put checks in all three boxes on every part returned.
I did the pre-public beta and turned in a problem for 10.10 that was addressed in core services.
10.10 was installed fresh on a second partition and I checked in on it every so often to update it. It wasn't until GM when I deleted the second partition and upgraded 10.9 until I started having trouble.
So far my MacBook 2012 has had a few issues with 10.10 GM including, a few graphics artifacts, wifi dropping, hostname auto-incrementing, disk utility unable to remove a second partition on the fly like 10.9 was able to do, and something not playing right with QuickBooks 2015. (QB website stated 2015 was compatible with Yosemite, however that isn't what I found out. QB is more graphics than financials and I think they weren't ready for the graphic system change in 10.10.) Back to 10.9 I go. I hope 10.10 didn't screw up my Time Machine backup. Only another 4 hours until I know.
I've got a MacMini that was also upgraded to 10.10 without any problems. It is in server mode so it doesn't power itself down. It also is not wifi connected. It doesn't connect to any iDevices.
My guess is a big driver pack update will fix a lot of 10.10 problems.