Comparing videos between iPhone 5 and iPhone 4S.
This video tests indoor and outdoor lighting, front and rear camera, depth of field and also the difference in stabilization.
The iPhones were on top of each other (overlapping) to have an equal comparison. The video was not altered, only cuts and resizing were made.
I suggest watching the video in 720p or 1080p only so you can have a real notion of difference. As we know, both rear cameras (iSight) have 8 megapixels. On the front, however, the iPhone 5's camera is a FaceTime HD, versus a VGA on the iPhone 4S. In addition, we can clearly see the advancement in the new device in virtually all tested features. (MacRumors)
Equipped with an infrared camera, Chipworks analyzed the device and found the brands of the camera manufacturers. The rear (iSight) made by Sony, while the front supplier (FaceTime) OmniVision are both long-time partners of Apple. (9to5Mac)