All it takes is one grain of sand stuck to the bottom of the top display to completely destroy the bottom display. And forget about a screen protector on that screen since these are supposed to be flush, top-to-bottom with no room between.
The first thing that popped into my head when I saw the top picture was a lawsuit from Samsung and Apple for just the look of the device. It kinda does look like a Galaxy S II at the top a little bit.
I think this phone looks pretty nice, can't say battery life will be stellar though especially with the hardware needed to properly and smoothly run both displays. Most devices have lag problems with just one but I normally assume that's bad optimization of Android on the company's end.
Something like this has been done previously in Japan with the F-04B, but the manufacturer of that model (Fujitsu) faced issues with keeping it slim as well as methods of attachment. The concept model used magnets but in the production model, the camera module hooked onto the main body of the phone.
In order for this to become feasible however, battery tech would have to improve greatly.