I'd give it a 3.5 if I could. Great acting. Good pace. Interesting (and true) story. Adds up to a good movie. The acting deserves special mention, it was truly outstanding. While the movie's unique device is to tell the story dispassionately, I still balk at the lack of character development. The only social angle we get on our bored suburban teenage protagonists is that they have a lot of sex, use drugs, play video games, and just generally remain shallow and naive.
That said, the climax is alarming, incredibly raw, and definitely nerve-racking. Overall, Bully is a life-like and engrossing film, yet incomplete in its story, and should NOT be viewed by those who are easily offended or upset by bizarre, grotesque, or graphic violence, sexual imagery/dialogue in film.