The motion sensors on Apple's iPhone 5s are not working properly and delivering inaccurate results, if a new report is to be believed.
The various sensors of the phone, including the Level, Gyroscope, Compass, and Accelerometer, were put to test by
Gizmodo, and the site found out that the readings were way off compared to the ones taken by the iPhone 5's sensor. Both the phones were running iOS 7, which implies that it's not a software problem and cannot be fixed through an update.
The site found a major difference between the iPhone 5s' internal inclinometer/ level readings and a real measurement of inclination. Compared to a Stanley spirit level, the iPhone 5s level's reading in iOS 7 compass software was 2-3 degrees off. The reading was accurate on the iPhone 5. The results were similar even on a third party app. Same was the case with the Gyroscope impacting gameplay on the phone.
Testing the Compass, Gizmodo found out that there was a difference of 8-10 degrees between the iPhone 5s and iPhone 5. Compared to a real compass both the phones' readings were off but iPhone 5's reading was more accurate. This issue could affect mapping and navigation apps leading to differences in location detection.
The iPhone 5s' Accelerometer registered more latent motion than the iPhone 5's Accelerometer. This would again impact gaming and motion tracking-based fitness apps.
It's also possible that the iOS 7 software is not accurately calibrating the iPhone 5s' sensors for which a firmware update bringing a fix could be released. However, different users are reporting different levels of discrepancies on forums. It's also possible that the sensors have not been calibrated properly in the factory, as the report notes.