Samsungs alarm clock sucks!
I hated my HTC Thunderbolt for a good 28 of the 29 months I used it for, but I am cheap so stuck out my 2 years. One thing I did kind of take for granted though was the alarm clock app they had on the Thunderbolt. I could set as many alarms as I wanted, I routinely used 5-6, set different ringtones, different volumes even if the phone was muted they would go off, and most importantly in the entire time I used it, I never had it fail to go off.
So I get my s4 in the mail from Verizon, and can't get it to activate. Take it in to the store and they took a solid 2 hours to get it to work too. Get home and play with it for a bit, and found a samsung alarm clock app. 1 setting for one alarm. I could not get it to set multiple alarms. Not a huge deal, I just have to make sure I don't ignore the first alarm (I tend to set 2 alarms in case I turn it off when I thought I snoozed).
Next morning I wake up in a panic. You know how your body just knows you overslept. 4 minutes late, so not a big deal. I'm kind of surprised really. Check the alarm and it is set to go off in 6 days 23 hours and 55 minutes. Thinking I just set it wrong, I played around with it some that day. Alarm never (not one time of the 5 I tested it) went off, I could set it for a few mins away, and it would tell me 2 minutes until alarm. 3 minutes would pass and I would check again and it would say 6 days 23 hours and 59 minutes until it goes off.
TLDR version. Stock alarm sucks. Use only if you don't care about missing stuff. Looking for a good alarm clock app, one I found that seems ok is ad supported. For an alarm clock...