My almost 15 yr. old daughter has a cell phone and has since entering Junior High. I was a bit skeptical at first about her having it. I have since changed my mind! I would advise getting unlimited texting as that is what kids mostly use. Here is a list of the pro's and con's as we have experienced them:
Pro's: No excuses about there not being a phone available or someone's battery being dead because I know she keeps hers charged. If she's out with a friend and decides to go to another friends house, she sends me a text to let me know. It's easy for her to get friends and their families phone numbers and give them to me. If I will be late picking her up or need to send someone else, I just send her a text...she checks her phone between classes, I also send her reminders of when I will pick her up for doctor appt's so she won't be late meeting me at the door. She doesn't like being without her phone so it makes for a good punishment to take it away or at least threaten to if she doesn't do her chores lol. I can check her phone at any time to see who she contacts and get their numbers. A now former friend (who I never did like) had ditched her at the zoo during this girls birthday party along with another kid and she was able to call me right away to come get her & the other kid, she often sends me texts or pictures to share with me what she and her friends are doing, when she's out and about I can contact her at any time, when she's gotten sick at school, she can contact me right away and let me know, which is great because one time the school thought she was trying to get out of a test and refused to let her stay in the nurses office or contact me (she gets mirgraines on occasion) she sent me a text and I went to the school with her medicine in hand and had a chat with the school people while she threw up in the garbage can because of the migraine having gone untreated for too long. (She's not a trouble maker, hasn't ever been in trouble and is a good student so why the school thought what they did is beyond me...all I can say is that the schools are more used to dealing with bad kids than good so they automatically tend to think the worst of everyone anymore). I had never thought that her having a phone would be such a good thing but it has really been a great tool for her and I to keep in constant contact with each other and has helped us during situations that we never imagined that we would be dealing with, such as with her former friend and the school.
The con's: She likes to text her friends after bedtime so I have had to take it away and shut her phone off, she texts during family gatherings unless I've told her to let her friends know beforehand not to contact her during that time, she let a friend borrow it and got it taken away during school hours so I had to go in and get it back from the principal, the phone she has has many problems and we are always taking it in to be fixed (at no cost to us, just the hassle of having to take it in and get a loner phone and waiting for the repaired one to come back in, so be sure to ask about the phone before hand to make sure it's not one that typically needs lots of repairs and don't get anything that's new on the market, get something tried and true).
Many of her friends have phones that need pre-paid minutes. Their parents make them earn the minutes and it works well for them. I am glad that she has the phone as it has come in handy in a pinch, I am able to contact her when I need to and she can call me when she encounters trouble or to let me know who she's with and where she's going (her friends family often take her out to dinner or to the movies with them). Because she can take pictures or contact me at any time, she shares more of her life with me too. I get pictures of her and her friends being silly, texts telling me something funny they did, etc. I love that she has the phone and that through it, I am able to be more a part of her life than I would have been otherwise. On another good note, she keeps in constant contact with her cousins who live far away from here and with other family members as well as she often calls her grandparents just to chat! It has been way more of a good thing than a bad thing for us and I am glad that I changed my mind and got her the phone.