Very interesting concept!
I'm not sure about price, seems like a big tab when you add a basic shoulder strap, $60.00, seems like a lot.
I'd also have to see how the shoulder strap works in conjunction with a smart cover, seems like it may be prone to flapping open or coming off completely. Perhaps this case is like the smart feather shell that holds the cover on.
Think I would stick with my otter utility strap as it uses's all four corners of the ipad.
Is it a thin shell or thick? Add much weight?