I have a 4s and am very happy with it and only use it for calls, music and the odd picture and video here and there and the 5 adds nothing I want and I highly doubt the 5s will add anything new either. In order for me to ever get a new phone - Apple simply must bump the space options or improve battery life. I don't care about processor, screen size or anything else.
By the way, night shots on a iPhone 5 are better compared to the 4S. But yeah there's not much difference.