I'm on the fence about upgrading. I have not loved Mavericks, but am a little weary of the bright blue Helvetica monster that is Yosemite on my two 1440p non-retina displays. I tried the beta on my MBA and after a while it did not look "so bad" so maybe it will be ok on the better 1440p screens. The reviews I've seen seem to focus on iOS integration and the "new look" but don't talk a lot about under the hood stuff. Anything of note that we know of? Especially in regards to graphics drivers or OpenCL?