That screenshot captures the most useless feature I've ever seen."
Why is it useless?
Why is it not useless? It adds nothing to productivity, has barely any functionality, and is potentially the most confusing interface style I have ever seen. "Multiple desktops" are one thing. "Huge spinning cube with each face able to carry into the next" is absolutely inane.
Linux vendors need to work on their 2D UI design before worrying about transitioning to 3D. It's almost as if they added this feature simply because they could, rather than because they had any compelling design reason to do so.