I'm a fairly regular (though not extremely skilled) user of 3D CAD software. I suspect that this would extend the time to perform simple tasks when compared with a 2D & a 3D (space) mouse.
The fact that Elon Musk doesn't design a part in his demo is telling. That part is VERY simple to create in today's UIs: a simple revolve of a cross section with a couple of patterned extrusions around the circumference. I see 5 distinct operations, and a more experienced person could probably make it in less. Just a couple minutes for even an amateur like me.
I think other 3D users will agree with me that this will increase the time for common tasks like selecting edges for radius/chamfer/draft and the critical sketching/dimensioning of cross sections for extrusion. A mouse pointer is so precise. To get the same level of accuracy with this system, you'd have to zoom in several times to make sure the correct feature/surface/edge is selected before you can perform any operation.
Creating the 2D drawings, which are still required for actual production, will also take much longer with a system like this.
There are many analogies for non-3D users, such as art programs or scale model/figure painting. I bet this is very similar to a programmer watching Johnny Mnemonic or Swordfish and saying "yeah, hacking doesn't work like that, that's ridiculous".
I've pre-ordered a Myo Armband and I'm hopeful that I can make it do some cool things with my CAD station. But for now I don't see this as anything more than a way to show your Director or VP the cool work you've been doing or communicate issues/challenges in the mechanical design to non-MechE's.