We got our daughter one when she was 9. I was initially against it in principle. But really it has only added $10/mo to our bill so it's not like an extreme extravagance. Since grandma lives in the next state and they like to talk to each other it's free because they have the same provider and it's unlimited cell-to-cell. Also when we lived in Fort Worth it the neighborhood was a little shady at times so the rule was she had it on her at all times when she was out in the neighborhood and when she was walking to and from school. It was also a rule that she check in with us when she got to school property to make sure she made it there without a problem and also that she call us when she got out to let us know she was walking home. So it serves as a security measure.
Problems: She's on phone # 4 in year 2.
1. The first phone did ok but it fell out of her pocket when she was riding her bike and behaved oddly for the next 6 months until it eventually crapped out.
2. So we had to get another which was an old one of my wife's that she saved the last time she got an upgrade....3 months later and it was trashed. (this wasn't exactly her fault though)
3. Then we got a replacement from our provider....lasted 4 weeks before it was washed in a load of clothes...twice. It hadn't even shown up on the statement yet. But we managed to dry it completely out and get it working again....amazingly. But when we went to see grandma over thanksgiving she left it there.
4. While we were trying to get phone number 3 dried out one of our neighbors gave her an old one to replace it in case it stopped working....which it's trying to right now because the mic isn't picking up her voice very well as a result of getting wet.
She doesn't text. She doesn't over do it on the minutes. She doesn't talk to people she's not supposed to (I know because I check the call records). But she's hell on the phones themselves. From now on if a phone gets killed because of her irresponsibility it's on her dime.