The most interesting thing about the iPhone 5 launch is not how little it's perceived to have changed over the prior generation, but why.
Roughly speaking, the iPhone accounts for around $60Bn of Apple's annual revenue, and that $60Bn is pretty cyclical in respect of the fact diehards upgrade every year and no-so-diehards every other year. Which means a huge chunk of that $60Bn is derived from existing customers and, more precisely, existing customers who know what they like. And they really like their iPhones.
So, you'd need brass balls to gamble $60Bn a year by making major deviations to a recipe that works. Which is a not insignificant problem for Apple.
We usually associate a lack of innovation with organisations that are in either decline or distress, or both, but the iPhone 5 is a great example of how creating the world's most successful product can lead to a situation where you need to deliberately retard innovation.
Which is actually a fascinating notion in the sense of Newton's third Law of Motion; where every action results in an equal and opposite reaction.