A week after its initial launch iOS 7 had made its way onto more than 60% of iPhones according to data collected by Mixpanel. iOS 7’s adoption rate is greater than that of any prior iOS release. This could be a strong indicator that a majority of people desired changed for their iPhones since they have been interacting with the same style interface on their iDevices for years now. Currently, the percentage has grown to nearly 65%. Despite the significant adoption rate it would be interesting to see how many of the users that update would want to downgrade back to a previous iOS and whether it would be based solely on the UI appearance of iOS 7.
See the stats here.