See this article at Slate for an unusually detailed (for a Web article) look at the highly controversial leftist propaganda piece. Here is an excerpt:
To describe this film as dishonest and demagogic would almost be to promote those terms to the level of respectability. To describe this film as a piece of crap would be to run the risk of a discourse that would never again rise above the excremental. To describe it as an exercise in facile crowd-pleasing would be too obvious. Fahrenheit 9/11 is a sinister exercise in moral frivolity, crudely disguised as an exercise in seriousness. It is also a spectacle of abject political cowardice masking itself as a demonstration of “dissenting” bravery.
… And I thought the end of the Cold War had also brought an end to the great age of propaganda!