I'll tell you why so serious

At first rather annoying in its heavy emphasis on reenactments, this movie ultimately proves fascinating, simply because the complicated, highly dramatic tale it tells still almost defies belief.

This film is so real. It treats its characters with so much care and sensitivity.

Watching it is like watching the spectacle of a class clown at their best: you laugh at their jokes, instigate their defiance, and "ooooh" when they get in trouble.