A few problems...
1) It would be almost impossible to use on a flat surface because it would rock back and forth.
2) The headphone jack on the side would be a problem if you had it in your pocket. For that matter it would be a problem just holding it in your hand.
3) There are no dimensions listed, but the camera on the current iPhone is the thickest component. Which means that either this concept can't be, or it's actually much bigger 2-3x the size of the current iPhone.
4) There's too much wasted space. Sure, the curve feels good, but you're removing battery (or other components). Unless like #3, the concept is actually a big enormous iPhone.
My problem with most of these concepts is that the designer didn't do any studying of the components of the iPhone. They don't design anything that's feasible, and if their designs were to be attempted, the product would suck because of things like making the iPhone 2-3 times bigger to fit the camera in it.
I mean really, all this guy did was take the existing iPhone and carve off some of it to make it curved. That's not doable in real life.
If that qualifies for a concept, here's my ultimate concept -> .
That's right, it's that little dot! Apple could advertise it as the smallest phone, or anything for that matter, ever sold ever.
It looks great and seem like it would be very comfortable. Much better than other concepts showing one side thinker tapering to a thinner side is a horrible and uncomfortable design. Over all it looks nice and I hope the end product looks like this.
At first glance, WTF? Then, as I picked up my magic mouse and held it like an iPhone, pretending to type in portrait and landscape mode, holding it up to my ear to speak... it actually is quite a compelling ergonomic design. As cool as the 4/4S design is, I really miss the ergonomics of the original iPhone.
Totally useless design... Who the hell would like or use a stereo port on its side,,, also one little drop and say goodbye to the phone due to is thin edges.