I've noticed quite a few things that are a big deal for me. I have concluded it's hardware related because: A) I have had 2 iPhone 5 's and they behave the same. My wife's and daughter's behave the same. B) My 5 and 5S had the same version of iOS when testing. 1) The ambient light sensor seems to be a better sensor or better implemented in hardware placement/usage if the same component as the last as the phone makes much better decisions regarding adjustments to brightness. 2) The fingerprint sensor. I'll never go back to a phone without one. It's like the phone has no passcode at all even though it is protected. Super easy, super fast. 3) The touchscreen is MUCH more accurate. Way fewer typing mistakes with the keyboard (like 85% less.) At first I though maybe Apple was using parallax to adjust touch targets based on yaw/pitch... and if they aren't they should, but with motion off (reduce motion on in settings) the 5S is clearly better. I have so many typing mistakes on the iPhone 5, I began to wonder if my fingers got fat or something or if my body had less moisture content than it used to since I would have to hit button several times without explanation. When I switch between the 5 and 5S, the touchscreen issue is glaringly apparent for me. I rule out a bad 5 since both of mine, my wife's and my daughters all behave the same. This is what the 5 should have been. I am ALMOST convinced to only upgrade on the "S" cycles from now on, however as a developer that isn't realistic. The biggest deal so far is the touch screen accuracy and response.