Mavericks ran like complete ass on my 2009mbp (HD video performance was abysmal, HDD performance was awful even with SSD, no way to swipe back in Finder, everything about it felt broken), I was scared to update to Yosemite but it is running very well, as good if not better than ML. I thought the all the blur would slow the machine down immensely considering how bad the gpu performance was in Mavericks but it doesnt impact it at all.
Only problem Im having is the wifi disconnect when waking from sleep which is supposed to be fixed in todays update.
Only problem Im having is the wifi disconnect when waking from sleep which is supposed to be fixed in todays update.