One of the best features is that when you save the alarm you get a little toast (not a fully notification) "Alarm set for 9 hours and 22 minutes from now." It seems pretty silly, and can be a bit depressing when the number is less than 8h, but is the most obvious indicator when you set the time wrong.
As someone who's really bad at time, I cannot tell you how often that toast has saved me from missing an important appointment. Easily the best feature any alarm clock can have if you ask me.
