From the previews I thought this would be your standard sappy good vs evil movie. It's NOT. It's about friendship and relationships, and shows us that nobody is perfect and we all make mistakes.
Age appropriate - It's about high school and should be viewed by high school students. I watched it with my 7th grade daughter and found a few of the sceens inappropriate for her. Like a brief talk about sex and drinking at a party. The mother also appears as the heroine's thoughts (much like the angel and devil cartoons) and the in the thoughts the mother is constantly putting down the daughter.
This movie shows us that nobody is perfect. The main character makes many mistakes, but most importantly she learns from them.
I highly recommend you watch this with your daughters and try to get her to discuss it with you.