Apple satisfied the primary complaints one could make about the iPhone when comparing it against high end competitors. The company also addressed issues that nobody had identified as areas needing to be fixed. And outside of technological improvements that will result in a new model next year, it's hard to point out any significant flaws in iPhone 5.
This is why comments are being focused on the new Lightning connector and the fact that users might want to buy an adaptor or extra cables, and the new Maps app: there's simply nothing to really dislike about the phone itself.