To quote IMdB, "Five high school students, all different stereotypes, meet in detention, where they pour their hearts out to each other, and discover how they have a lot more in common than they thought."
I have seen it before, wondered if I would think it is dated, but was really struck by the dialog. The screenwriters really made it work. I probably will watch it again, try to pick up on some more of the details.
Is it family friendly? Probably, if you have older kids, pre-teens and older. There is no sex if that is your issue. It is a teen movie, so there is some pushing and shoving, some potty mouth. There is also a marijuana scene that could be a great opportunity to talk with your kids. I think that is offset by what the movie teaches. In particular, it brings Ephesians 6:4, "Fathers, do not provoke your sons to anger", to life.