"An Unreasonable Man" is not a pejorative description in the context of this film. One is reminded that the qualities that make an activist effective, are the same qualities of persistence and refusal to compromise that make such a person infuriating in other circumstances.
Although the first half of the documentary is devoted to Nader's rise as the country's premiere consumer advocate, the crux of the film is Nader's controversial presidential candidacy in 2000 and the personal, public and political ramifications of his decision to continue the race knowing that he may cost liberals a victory of the (arguably) more palatable candidate.
Unlike the reviewer below, I did not see in the film any agenda to trash Nader for running for president. When the movie moves its focus to Nader's effect on the 2000 election and whether he should have run under the circumstances, both sides of the argument get a fair airing. In fact, if anything, I felt the movie makers were inclined to the pro-Nader perspective--that for the politics of corruption to stop, a principled stand must be taken.
Regardless of the side of the debate one might take, the filmmakers did a an admirable job of showing through historical perspective why Nader ran, and why he was unapologetic about staying in the race. His personal history, from his experience with the Carter administration, the debate debacle, and his basic uncompromising personality and dogged pursuit of his goals, illuminate the motivations behind the 2000 Nader candidacy.
Although the filmmakers obviously hold Nader in high esteem, particularly for his crusades on behalf of consumers, this is a documentary in the true sense of the word--it is not a propaganda film, it it does not beat you over the head with the filmmakers' views. While, it is sympathetic to Nader's political positions and would not be considered "balanced" by a hardcore Republican, this is not a Michael Moore type of opus to any particular position. It is an expository film that raises but does not resolve the issue that alienated so many former Nader supporters.