In normal lighting conditions the camera on the IPhone is not bad.
They are 2592 x 1936 pixels. It has a option that you can turn on or off called HDR or High Dynamic Mode where it basically shoots two photos with one slightly over exposed and one slightly underexposed. You can combine them back together and get better shadow and highlight detail.
This image is just a normal exposure "happy snap" from the iPhone, no HDR.
This is the center area cropped out.
The real downfall is low lighting areas.
For a camera that I always have with me it is not bad. It does real nice HD video.