New calibration methods had to be done for the iPhone 5s, and something seems messed up, or the readings get scrambled along the way to the M7, and maybe even in the new chip itself. Either way, the first iPhone 5s batches could be a few degrees off in their motion sensor readings compared to professional equipment...Source: http://www.phonearena.com/news/Apple-iPhone-5s-has-issues-with-motion-sensors-calibration-that-affect-gaming_id47966
