The word from mobile customer research firm On Device (as reported by TechCrunch) is iOS 5 eked out a bit more customer satisfaction than iOS 6 has thus far. The company checked with 16,000 iPhone users, and even though it's only a small deviation, it's the first time there has been a dip in the numbers measured by On Device.
iOS 6 users have a reported satisfaction rating of 7.65, compared to 7.75 for iOS 5. When iOS 5 came out, that number was a jump from 6.93. In fact, every iOS release has seen an increase until now.
If I had to make a guess, I'd say it's all the negative talk of the new Maps app, and because such a large percentage of users are using their phones for navigation, any trouble with Maps can have an effect on user satisfaction. It's just one set of numbers, and the satisfaction change is very small. We'll see more data from more surveys in the coming weeks and see if a trend develops.