I understand why this was rated PG. The teen relationship development was cute and funny. However, most of the "dark" was taken out of the movie (probably) to make it appeal to a younger audience. Unfortunately, I think this hurt the movie.
Without giving away the details, the movie was OK for what it was, but it could have been so much more.
There was a lot of enthusiasm at the midnight show, so I will definitely watch it again in case I missed something that really makes it great.
But, for now, I'm looking forward to the next one.