^^^^ agreed, on a family plan it makes the most sense, it's nice that for those $10 up to 5 people can each have thier own 5 numbers to call...
personally, i had 1500 minutes before and was going over every once and a while. now i have myfaves and mobile to mobile and use about 150 actual whenever minutes.
also, my mom used to call my grandma long distance and would always have to wait till after 9 to call, now she has my grandma on her myfaves, and can call her house at any time during the day which is great.
for some people it makes sense, for others not so much. i would say most people make the majority of thier calls to 5 people or less. for those, this makes perfect sense.
like multiple people already said, to each his own. at least you have an option.