It's nearly impossible to judge a film fairly when controversy has already drowned it out before most people have even seen it. Based on a few trailers and scattered reports, Sia's directorial debut—a film called Music—was attacked for its portrayal of the title character: a girl with autism, depicted in ways critics called offensive, false, and harmful.
Music is played by young Maddie Ziegler, who is not autistic. The criticism here feels a bit unfair. Acting, after all, means pretending to be someone you're not. Sia apparently couldn't find an autistic actress suited to the role; that's a legitimate artistic choice, even if other directors have gone a different way.
The other complaint is that the character's autism appears quite severe. She's largely nonverbal, with some echolalia—she repeats only a few fixed phrases. She has rigid routines, numerous tics, and seems withdrawn from the world, partly because of the large headphones always on her head. Among the vast spectrum of autism presentations, Sia chose one that reads "cinematically"—visible and clear to audiences. Questionable, perhaps, but not invented from nothing. Far graver is a scene where someone forcibly restrains her during a crisis. Though it demonstrates how ignorant the other characters are about autism, the sequence is so dangerous and wrong that Sia has promised to cut it.
The real problem is this: Music drives the plot, but she isn't actually the protagonist. She's a prop. The real main character is her older sister (Kate Hudson), who's supposed to care for her—despite being utterly incapable of caring for herself. The sister is an alcoholic, depressed, and survives by dealing drugs.
The second major character is an African neighbor who helps them both. Except he's Leslie Odom Jr., an American actor doing an affected African accent—a choice that somehow escaped any outcry. These two characters sink the film. The sister has countless problems, hinted at but carefully edited so her goodness shines through. He's almost saintly: so kind, so generous, so noble for such a cruel world. Two utterly flat stereotypes, conceived with genuine awkwardness. Music, unable to express any personality of her own, exists only to highlight their virtue.
Sia's main ambition is to enter Music's mind by rendering her thoughts as musical numbers—an idea that's partly defensible, though it's arbitrary to imagine how an autistic mind works based on neurotypical fantasy. At least it tries to go deeper than surface and tell autism in an original, creative way. It attempts to give the character depth. But as the film progresses and it becomes clear that Music is simply a vehicle for everyone else's story, even the musical numbers feel increasingly hollow. The idea, sadly, dissolves into banality.
There are plenty of reasons to criticize this film. The autism itself isn't the worst problem.