Long time fan of Digital Photography Review. It’s my first stop before I buy any new piece of photography gear. Agree with them or not, there is always something to learn from their reviews.
Their final word:
The iPhone 5s, running Apple’s fresh iOS 7, is an excellent phone with a very good camera. Image quality under most conditions is among the top of the class of “conventional” smartphone camera units: you have to look to the Nokia Lumia 1020 to find something that’s hands-down better across the board, though in good light the best 13-megapixel sensors do capture more detail.
The camera app is supremely easy to use, and the 5s’ powerful processing makes for class-leading burst speed and excellent responsiveness. Users looking to upgrade from older iPhones shouldn’t be disappointed. That said, there’s nothing in the 5s that changes the fundamental balance of power in the mobile photography world: users committed to other OSes won’t necessarily see a reason to switch.
About what you’d expect, I think. To really get a sense of the iPhone 5s camera, take a look at the gallery of 78 images at the end of the review. To see a particular image at full size, download the original (click the link at the bottom right of the image). In my opinion, some of these shots are stunning.