The ending of Whiplash offers one of the most electrifying movie moments this year. Centered on a rousing musical performance given by the film’s protagonist Andrew (Miles Teller), the scene is filmed and presented as a triumph, if a costly one. That's a daring choice from young director and writer Damien Chazelle, because Andrew, a student drummer, has been subjected to elite jazz-training hell by tyrannical instructor Fletcher (J.K. Simmons) over the previous 100 minutes.

At the end of the film, Fletcher clearly thinks Andrew's success is due to his approach of teaching-as-psychological warfare. He would undoubtedly exit the film and congratulate himself on a job well done. And the troubling thing, for viewers, is that he might be right to.

In Whiplash, jazz drummer Andrew endures a brutal, sustained campaign of bullying and abuse, both psychological and physical, at the hands of Fletcher, the conductor of his conservatory's prestigious studio band. He eventually washes out under the extreme pressure and, at the urging of his concerned father, anonymously gets Fletcher fired for abuse. In the final scene, Andrew ends up at Carnegie Hall subbing in for Fletcher's concert band. It's a final cruel ruse orchestrated by Fletcher, who wants to humiliate Andrew publicly by cueing him up to play the wrong music.

But then Andrew turns the tables. He leads Fletcher's band into an incredible rendition of the song he was prepared to play. It's a powerful moment, despite the wringer the audience (and Andrew) has endured the whole movie. But there's also no question, as the audience watches its hero furiously bang out Fletcher's perfect tempo, that Andrew’s spirit is broken. Great art, or at least a great rendition, has been achieved, but at the total cost of the teen’s humanity. At the beginning of the film, he's obsessively driven and introverted, but relatably so; he works up the courage to talk to a girl he has a crush on, and kindles a brief if awkward relationship with her. He struggles with dinner party conversation. But as Fletcher begins to grind away at his confidence and sanity, Andrew withdraws further, breaking up with his girlfriend in robotic fashion and behaving more erratically until suffering a mini-nervous breakdown.

Fletcher is a terrifying, commanding figure throughout the film. Simmons is always clad in a tight black t-shirt that emphasizes his build; when we first see him conducting the studio band, he raises a hand in the air and the camera swings around him, as if at his beck and call. Director Chazelle often shoots Andrew as an isolated figure surrounded by negative space, emphasizing his enforced solitude, but Fletcher is far more dynamic. Simmons, doing some of the best work of his career, keeps you hanging onto Fletcher's every word even when you know his goal is to chisel away at Andrew's self-assurance. There's a scene later on in the film where he clearly explains his (predictable) modus operandi to Andrew: Fletcher believes great musicians can only be forged in a crucible of fear and torment, and says he’s just trying to get the best out of the best.

In an interview with The Dissolve, Chazelle says some of the inspiration for Fletcher came from his own high-school music instructor, and while he explicitly states that he himself doesn't share Fletcher’s mentality, he concedes, "I do believe in pushing yourself." Practicing music, he says, shouldn’t be fun, since you're supposed to be hammering away at your flaws.  "If every single thing is enjoyable, then you’re not pushing yourself hard enough, is probably how I feel," he explains. "But this movie takes it to a extreme that I do not condone."

In the same interview, Chazelle says he thought Whiplash, especially its finale, followed the arc of a sports film. The comparison is apt: The hero is brought low and then surges back in the grand finale, winning a great victory at an undeniable physical cost.

That's perhaps where the problem lies for the movie’s critics. "We're supposed to leave our seats feeling just a little admiration for Fletcher and his alleged standards, because perversely, they really do tease out some greatness in Andrew," Stephanie Zacharek wrote in The Village Voice. "But Fletcher's tactics have nothing to do with talent, or greatness, or even just the complicated dynamics of playing music. He's just a cartoon bad guy masquerading as a complex one."

To others, the implications of the final scene’s triumphant tone were less disturbing and instead flat-out comedic. "It's obvious that Chazelle fully intended for Fletcher to come across as a repulsive, psychotic caricature, but it becomes problematic when those same traits begin eliciting big laughs," Adam Woodward said in Little White Lies. "For all that Whiplash boasts technically impressive live performance adrenaline highs, which effectively capture the thrill of watching a group of musicians play in total harmony, it is too often guilty of distracting its audience from its self-conflicting message."

Whiplash raises the age-old question of depiction equaling endorsement. Just because Fletcher screams homophobic insults into Andrew's ear and throws chairs at him while he's drumming doesn't mean Chazelle finds him remotely sympathetic, even if his behavior produces results. Many critics have compared him to a drill sergeant and the film to Full Metal Jacket—Chazelle himself has acknowledged the comparison—a similarly horrifying, brutal film where you can't help but be impressed by the single-minded effectiveness of the authoritarian monster.

But that's a film about war, and Whiplash is about art. The audience spends the whole film wincing at Fletcher's tactics. Despite Fletcher’s claims that his abuse is in the name of making Andrew a great jazz artist like Charlie Parker, his hypocrisy is apparent. In the final concert scene, Fletcher is not trying to get Andrew to rise to his challenge—he just wants to humiliate him. When Andrew shakes off the nightmare of being given the wrong music and playing out of sync with the band, it surprises Fletcher as much as anyone.

But that bravura ending—a hyper-masculine celebration of punishing dedication and success in a great battle of wills—is impossible to shake. As much as we've regarded Fletcher with horror throughout the movie, Andrew's ultimate achievement is that he finally impresses him, without caveat. Andrew is tragically wasting his effort on this sociopathic void of a man, but you can't help but be stirred by his superhuman effort all the same. Whiplash treads that uncomfortable line as tightly as possible and leaves the audience feeling a little queasy for admiring Andrew's victory, no matter how Pyrrhic it might be.