American Splendor is a narrative film - a biopic with actors portraying real individuals, telling a true story. Is this documentary? I would argue not, but here are definite chapters of the film that are documentary style. Paul Giamatti plays Harvey Pekar, the author of the American Splendor underground comic, but at times, the story is intruded upon by interviews with the ACTUAL Harvey Pekar and other characters involved. This break in narrative fashion is unusual, but definately something I'd expect from an HBO film - playing with conventions.
Often Pekar is explaing something that just happened in the film, or elaborating on an incident. These intrusions are shot in a style that viewers are meant to read as "documentary" - a classic talking head in a studio recounting an experience. The interview sections of the film are supposed to led a sense of truth to the portrayals going on with Giamatti and Hope Davis, as if their acting is also "docureal." It's an effective device, if disorienting at times. In one sequence, Giamatti walks onstage in a TV interview, then the REAL Pekar's interview is shown (in the same clothes!) and hen when he exits the screen, Giamatti walks back in and asks Davis's character how she liked it.
I am still convinced that this does not constitute documentary in its own right, since Giamatti is still PLAYING Pekar. Unlike Milk, however, American Splendor does not story into the realm of the unknown very much (Like Milk's personal life) - that is to say, it stays more to the documentary realm as narrative films go, instead of elaborating on aspects of Pekar's life for dramatic emphasis. It was entertaining and informative - usually a word I reserve for documentaries, and HBO did a good job of blurring the lines between the doc and the narrative film.