Dean and Shiffrin's documentary is a must for anyone interested in the mind behind the story of the main feature, and anyone interested in Selby's written works. The documentary has a thematic organization yet flows smoothly, while covering many aspects of Selby's life, the social context of his works, the obscenity trials, adaptations into films (including several interviews with people who worked on Requiem for a Dream) Interviews with Selby himself and especially footage of Selby reading his works on stage really add to the understanding of his works. The documentary will make you want to go out and read the books if you have not already. The low budget style just enhances the reality of the interviews, for a writer who was pretty much always on a low-budget himself. The camera and sound work is excellent, they clearly know how to get the most out of their available equipment, as you may expect from the author of the $30 film and music school books.
I'll not review the main feature, it has been adequately reviewed elsewhere. It's great to have it as a double disk here in the UK because you will appreaciate the main film more by seeing the documentary.