A couple of things are notable about this image, I think. First, in this very contrasty shot, with direct sunlight coming through a window, you still get decent detail in some of the shadows. Look at the painting in the background, for instance.
And the resolution is very good. Here's a crop of the same shot:
The fur and the paint texture hold up nicely in this enlargement. I didn't add any sharpening. Click on the image to view it larger.
The iPhone has some issues. The very-low-light pictures I've taken aren't great but, c'mon, this is a small sensor (4.89 by 3.67 mm, according to AnandTech). I've had one lock-up unrelated to the camera, and the voice dictation--great when it works--mysteriously refuses to be available in the Notes application at times. Overall though, and in particular regarding photos, I'm happy so far.
My previous iPhone photos are in this post.