The stock alarm clock definitely has issues. Sometimes the snooze works and sometimes it doesn't. I've had it set to two 15-minute snoozes since I first set it. Most of the time, when I hit the snooze once, the alarm will go off again 15 minutes later, but if I hit snooze again, the alarm won't go off again. Then for like 4 days, the alarm wasn't going off at all, even the first time. I kept checking various things like what programs were running etc., and then I just decided to power the phone off and back on, which fixed it. The alarm started going off again, but yesterday I hit snooze once and the alarm didn't go off again that morning.