There are two things I never liked about Unity, the Amazon thing, and the super shallowness when pressing the "windows" button to launch apps. It only works reasonable well on super fast machines with a really good graphics card. I don't understand why it takes up to a second before I can start typing on almost any machine I use. And it is only a overlay which could almost be static.

Gnome on the other hand does the whole live animation thing for every window on every desktop and it is still mega fast even on my oldest machines. I press the button and basically instantly I am able to start typing and launching the app I need.