The summer of iOS 7 is nearly over. Apple is expected to announce the new iPhone on September 10, and it will likely ship with the final version of iOS 7 a week later or two at the very most. (That would put it in line with many developer guesses that September 23 would be the final finished version of iOS 7.)
Apple only has a couple of weeks to get everything together. In many ways iOS 7 has been very un-Apple-like. It was apparently rushed into production, after which Apple then pushed a massive change out to its developer ecosystem in order to get the new iPhone out at its appointed time with the new OS. As a result, complaints about iOS 7 design, bugs and functionality have been louder than with previous iOS versions.
Apple has faced tough times with the iPhone before (remember AntennaGate?), and come out on the other side with a great product that millions of people bought and loved. None of the problems that iOS 7 has faced are impossible to overcome with a little time and patience.