I have never read Gore Vidal's novel but was always curious about the film, as it was so "controversial" (and for many years unavailable) Now it's easily available on a DVD with a lot of nice extras. Watched it last night, it's just fabulous! I think it does rely on a bit of film-history geek knowledge, but it is well worth a watch. The film very much stunted Raquel Welch's career and I think a few other heads rolled too...and I love a train-wreck of a film
Just thought I'd mention it in case anyone has been sitting out there still thinking it's unavailable!