From what I've seen this one didn't get that many positive reviews. I for one enjoyed myself. Maybe because I'm OK with the lack of resolve for the drama at the end.
The movie takes on a serious issue and puts the Carrie spin on it. I was very pleased with the color design (esp. early in the movie) which helped making it look not quite so generic. The direction was fine and the acting from the lead girl aswell. As for the adults.. let's just say that it felt a bit forced and akward from time to time. The main issue for me was the ending. The role reversal came out of nowhere and the results of it were quite dumb. With all the foreshadowing they could have gone for a proper ending instead of biting trough everything again.
All there is left for me to say is: best birthday party, ever! (and why would you dedicate this movie to "Grany" :O)??