Once again, commonsensemedia over exaggerates. The language is strong, yes, but not for a PG-13. There are no f-words in the movie. Also, there's was a lot of suggestive dialogue in the movie, and a few sexual scenes, but no scenes actually depicting sex. It should not have had an R-rating. PG-13 is appropriate. However, I think it's disgusting that there are 11 and 12 year olds who have seen this. Even though I think the rating is appropriate, I wouldn't have let a 13 year old watch this either. It's probably best for 15+. I saw this with my best friend when I was 15, almost 16. I would never have watched it with my mother. I watch a lot of suggestive things with my younger sister, who is 12 (and watches things like Friends regularly) , but I would never have let her see this. And to all of the kids whose parents won't let them see this: Don't feel bad. You're not missing much. Rachel McAdams is the only actress in this worth watching, and the whole movie reminds me of why I hated high school.
All in all, for your average 15-17 year old, this would probably be a fun movie to see with friends, NOT a younger sibling or parent.