These are pictures comparison on the same location using iPhone 4S and iPhone 5 (as shown in the iPhone 5 Show Galery)
The same picture was taken using iPhone 4S by Scott from DPreview.com when traveled to Big Sur in California.
As shown, picture taken with iPhone looks sharper and it capture more space as iPhone 5 uses 4.1mm lens for a 33mm field of view compared to iPhone 4S’ 4.3mm lens which resulted in a 35mm field of view. According to Dpreview, the image from the iPhone 5 was taken with ISO 50 setting compared to the iPhone 4S’ ISO 64 setting, which suggests that the iPhone 5 uses a new, improved, slightly larger sensor that is able to take in more light. This matches with Apple’s claims of iPhone 5’s camera being able to take better photos in low-light conditions.
Let wait for the actual review by the iPhone fan’s out there.