First glance: Looks cool.

First hard look -- it'll drive you nuts. Look at the one view you can see in the screenshot. They've got a 'disc' -- representing a folder, and maybe the five closest items are reasonably clear. The rest are smudges in the back.

How many files you have in a folder? Less than thirty? It just doesn't scale. I flip that view onto some of the archive directories I have, and I'll never find anything. 2D desktops at least offer the same scale to every object -- something a 3D desktop cannot do, without throwing away the very 'advantage' that 3D claims to have -- depth.
 
Remember this, kids. User Interface is *hard.*