The problem is not exclusive to the iphone 5s as has been the case around here. A lot of iphone 5c's including mine, are inaccurate. Easiest way to notice it is when you try to get a panoramic photo while you are rotating the device the arrow does all sorts of crap and the photo ends up a mess Given the fact that both iphone 5s and iphone 5c are experiencing this problem, I believe this is a good indication that we are dealing with a software issue rather than a hardware issue, especially since people thought it was the M7. And yes i have tested my iphone 5c with my iphone 4s which is working perfectly fine and reads everything excellent. The 5c is almost always -2 degrees off, and as I said, taking a panoramic shot is horrible I think apple is going to fix this in a future firmware at least i hope they do, or I am demanding a replacement.