It's a cool concept. I think the dual stick setup could be reasonable utilizing a detachable cord for the second stick, store the cable away unless you're playing robotron, etc.
It seems like the control pad setup is the worst part. Judging by the illustrations, it seems like it would be pretty awkward and uncomfortable, but I may be overestimating the controller's bulkiness.
As you probably realize, the shell is going to be the actual hard part.