I went and saw the movie with my sister, and I agree that I didn't like the rating. I don't see it was a PG-13 movie, but I don't see it as a PG movie, either.
I didn't like the movie at all, though. It was boring, and couldn't keep neither my attention nor my sister's. The only parts we liked were the ghost of Christmas future, and the ending. All during the movie before those parts, we were barely paying attention. I fee they rushed the ghosts in as well. All-in-all, it could've been a better movie.