Mountain Lion was crashing on my Retina MacBook Pro about every day, since I upgraded to Yosemite it hasn't crashed once. Only a single data point, but it appears to be a really stable release now.

I still have the impression that the GPU is struggling with the retina display though, I was just using a 4 year old MacBook Air and the display animations were smoother on it than on my rMBP. I do have it scaled up to the max resolution though, I think that makes the performance worse as the scaling is more complex.