So I am typing this on my 13inch Macbook Pro Retina with a fresh install of 10.10 ... So far I love the look however it is a very rough beta, pretty sluggish and for the first time I can actually feel heat and hear my little fan whirling as I download the iOS beta. I am sure they will get the kinks worked out over the coming weeks however I think they are off to a great start. One thing that I did notice is that if I set my display resolution to anything other than Optimal for Retina text becomes to small to read. It wasn't this way with Mavericks.