The bulk of Morris' documentary draws from a roughly 16-hour interview with Bannon. If you were to walk into the theater "knowing nothing about Donald Trump's former adviser (who he is, what he's done, what he stands for), you'd probably find him to be a fascinating, compelling, and at times even charming figure," Variety's Owen Gleiberman wrote in his review.
"If that sounds like a swipe against the movie, it is."
Gleiberman noted that Morris' film does "offer glimpses of his misdeeds, like a machine-gun montage of racially inflammatory headlines from the Breitbart website," which Bannon ran before joining Trump's campaign.
But those headlines are "folded into a picture of Bannon as a man of ideas whose quest is rooted in his devotion to the good solid working-class people he came from.
"Is that really who Steve Bannon is? That's certainly a part of him. Yet watching American Dharma, it's hard to escape the feeling that Errol Morris got played."
According to Gleiberman, Bannon is "no raging fire-breather" and is more "playing the role of alt-right Teddy bear."
Morris does not dispute Bannon's lies all that often, Gleiberman reported. The filmmaker also hands the reins over by including Bannon's commentary on clips from films he grew up with, such as Twelve O'Clock High and The Bridge on the River Kwai.
The Hollywood Reporter's Deborah Young had a more favorable opinion of American Dharma, writing it "is meant to leave its audience shaken, whatever side they're on."
She compared the film with Morris' Academy Award-winning The Fog of War, a look at the life and ideology of former defense secretary Robert McNamara, saying "it shows the same ability to engage the viewer in American politics through a strategy of detached passion."
Young also wrote that the excerpts from classic movies "have a common refrain: A man's gotta do what he's gotta do to be a hero, and he has to recognize an urge to self-sacrifice as his personal 'dharma' - duty, fate, destiny and obligation."
She felt one of the film's final shots "is a metaphor of wanton destruction that leaves the viewer with goose bumps. If anyone has doubts about Morris' own point of view, seeing that he never raises his voice to shout down his subject, this conclusive image should make it very clear where he's at."
The documentarian told the New York Times' Frank Bruni last month he made the movie because he "wanted to contribute something to the political debate ongoing." He said Bannon was willing to cooperate because he is a honey badger and "honey badgers don't care," referring to the viral meme.
During a news conference in Venice, according to the Hollywood Reporter, Morris claimed he has faced "hostile press" and thanked the festival for showing his film. He declined to comment on the New Yorker's decision to give Bannon the boot. But when asked about whether his film grants Bannon an unwarranted platform, Morris became "animated."
"If you're trying to tell me that this is evil or bad or pernicious or destructive, I'm not arguing with you," Morris said.
"If you're telling me that this is so deeply bad or pernicious we shouldn't talk about it at all, I say that's nonsense talk. You're wrong."
