Apple has also fixed the clipping save problem, where you drag a photo or text clipping to your desktop, and there was a massively long delay...
This was really a problem, and a huge bug I saw in previous versions of Yosemite.
I have been testing it out, and this "clipping drag-and-drop" bug seems to be fixed now, it saves instantly after you drag.
They have ALSO improved the translucency of menus, especially in dark mode, adding a blur effect behind the menu, and darkening the translucency. It looks MUCH better than the previous version.