Earlier quoted context omitted.
Yosemite is clearly first version fully optimized for Retina, potentially at expense of non-retina users. Every time I unlock my MacBook Pro I think "wow, this is gorgeous" (I have another one at work not updated to Yosemite, so I see difference every day). Unlike controversial iOS 7 update, Yosemite clearly looks better than the predecessor.
But very time I open my Air , I think "oh god what have they done".
I open my MacBook and think "the menu font is badly aliased, yuck" whereas the Mac Pro at work on Mavericks is still a joy to read. And trying to work out where a file is within Xcode is still as simple as right-clicking on the titlebar of the window (like all windows within Mac OS) but on Yosemite, how the heck do I do that????? The titlebar has gone!