I DO have the Alarms > Settings > Alarm in Silent Mode option checked, but when my alarm is in silent/vibrate mode, I don't hear an alarm anymore. This worked fine in 4.1.1.
Alarm volume, although separate, is locked to the ringer. So now If my phone is on Vibrate and/or silent the Alarm volume is automatically on silent along with Alerts and System.
Extremely annoying because I need my alarm in the morning without random texts/calls coming in at the wrong time.