iOS: A visual history
Perhaps the most remarkable thing about iOS is how similar the OS as it exists today is to the OS as it existed 2007, yet the number and breadth of features that Apple has baked in since then is mind boggling. Far from suffering from the “feature creep” that typically bogs down operating systems over time, iOS has managed to stay relatively snappy and is more internally consistent than anything else available today.
Amen. Pretty good read that shows the slow evolution to iOS5.