I am on a 4s and use my iPhone as my alarm clock. I have had 3 morning where it hasn't gone off in the last week. It worked the first time I updated to iOS 7 but the default sound was so soft I slept through it. I have since changed the tone and I am still have problems with it not going off. Last night I set again and it didn't go off but now it is showing me that the alarm is on for tomorrow morning. . 3rd party apps seem to work fine its just the built in alarm is hit or miss now. This is just a fyi to everyone that I would use another alarm clock if you rely on your iPhone.