First off, it's not in the theaters, it's just released on DVD.

The primary focus of the film is on why Americans kill more other Americans than anywhere else. It's about our society. Moore has nothing against guns. It's not an anti-gun movie. As the reviewer at DVD file put it, "it is an anti-Stupid People Using Guns to Shoot Other People movie."

I think it's great, and worth a rental purely for the animated short in the middle of the film from the makers of South Park (Matt Stone is an interviewee in the film as well).