The iPhone 5s improved upon the iPhone 5's camera in many ways. In our own camera comparison, I found that the iPhone 5s performed exceptionally well, especially when it came balancing colors and exposure. This was extremely evident in panorama comparisons. If you're still wanting more image samples, the guys over at Austin Mann have an amazing review of the iPhone 5s' camera posted. Not only do they have lots of sample images, they went straight to Patagonia to get them.
Much like our results, they found that the A7 processor and on board OIS in the iPhone 5s handled extremely well, especially in panoramas.
As you can see, the dynamic metering significantly impacts one's ability to accurately capture the breadth of lights & darks in a single scene. Time and time again I shot panoramas ranging across darker and lighter areas and this new feature worked beautifully.
They go on to test features such as slow motion video, burst mode, and more. If you're contemplating an iPhone 5s and the camera is an important feature to you, this is definitely a review you'll want to read.