According to Macitynet " The iPhone 6 will have rounded edges and the Standby button will be shifted to the right in order to ensure easy access when used with a single hand, given the increase of the display which will expand slightly on the short side of the device. We see however also two thin lines on the upper and lower edges that probably indicate a design similar to that of the iPhone, characterized by an aluminum back but broken by two bands in another material (maybe in the glass as the iPhone 5S) which should ensure proper operation of the antenna. Of note, the projection lens of the camera; the technical solution is the same as for the latest generation of iPod touch, remember, has just a protruding ring that protects the glass lens, reading to the surface of the back."
Most of the leaks pointed to the same new rounded design, which is pretty cool and incredibly thin.
