On the other hand, I'm still (on 10.10.2) experiencing severe window server bug where desktop just slows down to a crawl (all animations, window switching, missing control etc. run with less than 1fps) after some time of using the machine. Rebooting the system helps for awhile... and then it slows down again.
The issue seems to be limited to only nVidia equipped rMBPs, but honestly, I did not expect a brand new laptop (I have mid-2014) for 3kEUR to stutter just running desktop animations you know?
I have this too with Yosemite - mid-2012 rMBP, 16GB RAM. It feels snappy when freshly rebooted, but after a period of time (hours? Probably not minutes...) all desktop animations start to become really quite obviously sluggish. Swiping between spaces is painful.
You do not expect this on an expensive machine that is barely two years old.
I also have wifi dropout issues, Mail is increasingly slow and unpredictable, and iTunes... Christ, don't get me started on iTunes.
My wife's 4 year old MBP, with 4GB RAM, was usable with Mavericks but is now basically unusable with Yosemite. I'm hoping more RAM and an SSD might sort it out, but I'm not overly hopeful.
I've been a more or less full-time Mac user since about 2003 and I don't remember being this frustrated with their software before.
The issue seems to be limited to only nVidia equipped rMBPs, but honestly, I did not expect a brand new laptop (I have mid-2014) for 3kEUR to stutter just running desktop animations you know?