In the wake of a lukewarm critical reception for the the iPhone 5, a new survey of 16,000 iPhone owners in the United States, iOS 6 has contributed to an overall drop in customer satisfaction with Apple.

Customer research firm On Device found that iPhone users were slightly less satisfied with their devices' new software compared to users of the previous operating system, iOS 5. The drop in customer satisfaction is small, but On Device notes that it marks the first time Apple has faced such a drop.

"We have always seen an increase in device satisfaction as consumer[s] upgrade their mobile operating system from one version to another," On Device CEO Alistair Hill told Tech Crunch in an e-mailed statement, noting that traditionally, surveys also showed an increase in satisfaction among Android OS versions corresponding to the release of new software versions. The firm further adds that the drop in satisfaction from iOS 5 to iOS 6 appears particularly unusual compared to the increase between iOS 4 and iOS 5.

As expected, the main source of frustration appears to be Apple's move to replace Google Maps with its own mobile maps offering. Customers have not responded well to this change, and Apple has been under fire for a number of flaws in its Maps app.

Customers have also voiced some complaints about how the App Store now shows search results. Overall, however, customer concerns remain relatively quiet, and few users had complaints about something other than the maps app or the App Store results display.

Apple has long topped customer satisfaction surveys, emerging as a leader in nearly all research polls. According to another survey earlier this month from J.D. Power, Apple still appears to have a significant lead on Android devices, and iPhone owners are the most satisfied smartphone customers of all.

Despite the slight decrease in satisfaction compared to iOS 5, customer satisfaction still appears very high; although the new operating system has some disappointing features, they will likely not have a negative impact on future iOS device sales.