If anyone ever wants to make a serious biopic about George W. Bush, his relationship with his father would be a good focal point. The differences between these two men, plus their pivotal roles in U.S. history, have all the elements of high drama, and the examination of two presidents at once is a tantalizing proposition.

Oliver Stone tinkers with it in “W.,” but “W.” is not a serious biopic. It’s more like a sideshow curiosity. While most biopics assume the viewer already likes the person in question, this one assumes we don’t. The film, written by Stanley Weiser (with whom Stone collaborated on “Wall Street”), reads like a tragedy in which the central figure doesn’t realize how tragic he is — which is what makes it tragic for everyone else.

I have to assume Stone was kidding when he said he was making an evenhanded biography, the way Fox News is kidding when they say “fair and balanced.” Or maybe Stone, like Fox, is so convinced his point of view is correct that he sees no reason for nuance or subtlety. That makes for a fine screed, if screed-making is your thing, but it lessens the film’s value as a legitimate biography.

“W.” stars Josh Brolin as the Yale-educated oilman’s son who graduated from Drunken Frat Boy to Most Powerful Man in the World. Flashbacks take us to the 1960s and ’70s, when Dubya is quitting one job after another and displeasing his hard-to-please father (James Cromwell), who seems to have more faith in Dubya’s brother Jeb (glimpsed only once, played by Jason Ritter). His involvement in politics comes only after he couldn’t find anything else he enjoyed, and even then primarily as a way to make Poppy happy.

Intercut with this are scenes of the run-up to the Iraq invasion and its aftermath, with Colin Powell (Jeffrey Wright) trying to talk sense, Donald Rumsfeld (Scott Glenn) and Dick Cheney (Richard Dreyfuss) urging war, Condoleezza Rice (Thandie Newton) parroting back whatever Bush says, and Karl Rove (Toby Jones) lurking malevolently in the shadows (often literally: again, subtlety, not one of Stone’s strong suits). The earlier-set vignettes give us some insight into why Bush behaved the way he did: his desire to both please and outdo his father, commingled with good old-fashioned arrogance and stubbornness.

What nuance there is in the film comes from Brolin and Cromwell as the Bush presidents. Brolin’s Dubya is a petulant quitter, an uncouth brat who is suddenly expected to work hard after never having had to work for anything in his life. Ironically, his view of the world is as black-and-white as the director’s. He sees things as an over-simplified battle between Good and Evil, and while he means well — this version of George W. Bush is dopey, not conniving — he’s in over his head. Whether this is an accurate representation of Bush, I’ll leave for you to decide. But it makes for a fairly interesting movie character, and Brolin plays him as a real person, not as a caricature (though he does do a fine impersonation of Bush’s speech and mannerisms).

Cromwell gets more screen time than I would have expected. His George H.W. Bush is a calm, principled contrast to his screw-up son, and you can see in Cromwell’s performance the conflicting desires that fathers have for their children, wanting to challenge them but also protect them. Like I said, a serious examination of the dynamic between Bush 41 and Bush 43 could be fascinating.

Jeffrey Wright, Toby Jones, and Richard Dreyfuss are terrific as noble Powell, wormy Rove, and coldhearted Cheney, respectively. As Condoleezza Rice, Thandie Newton seems obsessed with doing a vocal impression that never really works in her favor. As the Bush women, Elizabeth Banks (Laura) and Ellen Burstyn (Barbara) stand by their men with the requisite weariness and occasional bursts of feistiness.

Factually, the film is basically accurate on the major points, in case you were concerned about that. If “W.” is a hatchet job, the target is the man himself, not the specifics of his deeds, which are mostly a matter of public record anyway. What makes him a hero to some and a villain to others is the interpretation of those deeds, and his motivations for doing them. That’s where a serious biopic would be more cautious and equitable. “W.” works well enough as drama (and occasionally as comedy), but it’s a missed opportunity to really explore some great American themes — all the material of a literary classic, squandered on a cheap paperback novel.

B- (2 hrs., 11 min.; PG-13, two F-words, moderate other profanity, brief violent images from the war.)