There are several issues with the case shown in the photos, however, including a round hole for the LED flash on the rear camera instead of the oval hole introduced on the iPhone 5s to accommodate the new True Tone dual-LED flash. Given the improved flash performance possible with dual LEDs, Apple will presumably continue to use dual-LED flash in future iPhones.
The photos also appear to show a slight change to the design of the earpiece area of the iPhone, with the proximity sensor window moving from next to the earpiece to next to the front camera. The ambient light sensor (not easily visible) is currently in this location. The dummy unit also shows the earpiece/camera/sensor features moved higher on the device's front, to the point where the front camera unreasonably appears to sit at the very top edge of the device.
The dummy unit depicted in the photos carries a screen size of approximately 4.7 inches if relative sizing compared to the iPhone 5s shown next to the model is accurate. That size is in line with circulating rumors, with the company also rumored to looking at even larger version with a display in the range of 5.5-5.7 inches.
The blog post also includes a list of features for the iPhone 6, although it appears to simply be a recitation of circulating rumors rather than specific claims.