(USA) Drama. Directed by Paul Weitz. Starring Paul Dano, Robert De Niro, Julianne Moore, Olivia Thirlby, Wes Studi, Lili Taylor. Category IIB. 102 minutes. Opened Jun 21.

Growing up with a writer father ain’t easy; I know it because I have one. But growing up with an absent writer-wannabe father who, in his delusional self-grandeur, thinks he’s America’s next Twain or Salinger—that’s a whole ‘nother matter. This is not some offbeat story someone made up for a sentimental movie, but the early life of Nick Flynn as the American playwright and poet recalls it in his acclaimed 2004 memoir, “Another Bullshit Night in Suck City.”

Despite ditching the awesomely pungent title of the book for the insipid “Being Flynn,” director Paul Weitz’s adaptation is insightfully written and headlined by the memorable performances of Paul Dano and a back-in-top-form Robert De Niro. While this artsy, low-key production is as uneven as the filmmaker’s career (which sees its peak in “About a Boy” and its bottom in “Little Fockers”), it captures the original material’s biting honesty and touching humanism, just not as exquisitely or powerfully as one would hope.

Set in 1980s Boston, the story is told in two dueling narratives—one belongs to Flynn himself (Dano), a 20-something drifter with a messed-up life, still haunted by the death of his mother (Julianne Moore); the other is from the point of view of his long-estranged old man Jonathan (De Niro), an narcissistic alcoholic and ex-con who dropped out of Nick’s life 18 years prior, and firmly believes that everything he writes is “a classic, a masterpiece”—albeit never having published a single word of it. Nick also fancies himself a writer, but keeps his dream and angst-filled scribbles secret for fear he will turn into a failure and a joke like his father. Having been evicted from his flat, Jonathan ends up living in the cab he drives—until that last resort is taken away from him after a car accident. Having fancied himself a “sought-after houseguest,” he becomes a veritable hobo, wandering the mean streets in the freezing winter for days before seeking a bed at a homeless shelter where Nick happens to work.

Their encounter is extremely awkward; their reconnection extremely painful. Here the duo of actors shines as their characters clash and the drama really begins. Dano, a consistently excellent and unique presence, is in his comfort zone playing a meek and quiet lad with some bottled-up rage, which bears resemblance to his roles in “L.I.E.” and “A Good Heart.” However, compared to Jonathan’s, Nick’s internal struggles and anguish are displayed in a rather superficial fashion that fails to register emotionally.

The array of supporting thespians, including Moore, Wes Studi and Lili Taylor (Nick Flynn’s real-life wife) are mostly capable, save maybe Olivia Thirbly (playing Nick’s sometime-girlfriend Denise), who seems unusually lifeless. But it’s De Niro, who’s probably in his most memorable role since “Heat,” that elevates the movie to a higher level. Having strayed through countless paycheck gigs in recent years, the veteran is finally giving an actual performance—one that matches his legendary reputation. The scenes of him driving a cab and getting into a fight are reminiscent of his glory days in “Taxi Driver” and “Raging Bull.” Even his epic rants, in a weird comic way, hold a theatrical bravado. With a portrayal that’s both heartfelt and convincing, De Niro’s Jonathan transcends an obnoxious caricature and becomes a sympathetic human being. If anything, it’s because of Dano’s and De Niro’s distinctive acting styles that their rhythms aren’t always in sync.

The bleak cinematography by Declan Quinn (“Leaving Las Vegas,” “Rachel Getting Married”) and the score by British indie musician Badly Drawn Boy (who also composed “About a Boy”) are both fitting. And the screenplay, written by Weitz himself, carries a poetic poignancy while wisely avoiding the sentimentality that could have existed in a less subtle movie. The film ends at the beginning of Nick’s writing career, which (as we know) has since taken off. And no one can deny that this father-son relationship, at once turbulently agonizing and deeply moving, has played a major role in his success.