The compass on my S4 is wildly inaccurate. First of all, if the phone isn't absolutely level, the compass reading is almost random and I can make the needle rotate through 360 degrees just by tilting the phone. If the phone is level, the needle might eventually settle in approximately the right direction but if I then slowly rotate the phone 360 degrees, it can easily end up with the needle pointing more than 100 degrees out. I just tried it now and quickly rotating the phone 90 degrees resulted in the needle pointing due E rather than N. I'm a keen walker and I sometimes use my phone for navigation. The GPS works really well but the compass is so inaccurate as to be completely worthless. Is this just my phone?