I switched to OS X 10.10 Yosemite a couple weeks after the Beta release. While it's been surprising stable, there are a few things I've had to tweak for development. Compiling a list here.
I followed this: http://jcvangent.com/fixing-homebrew-os-x-10-10-yosemite
I think this has something to do with the system update to Ruby 2.0.