The King of Staten Island stars Pete Davidson in a semi-autobiographical role

Star Pete Davidson has attracted some attention for reasons other than his work and talent - his relationship with Ariana Grande, his physical and mental health problems, and the fact his fireman father Scott died in the 2001 World Trade Center attack.

The 26-year-old has made comedy capital of the last, but obviously the pain is still deep. The King of Staten Island seems like something of an attempt to exorcise a few demons. In all sincerity, let's hope it helps.

There's a significant autobiographical element for Davidson: he co-wrote the script with Judd Apatow and Dave Sirus, the main character is named after his father, to whom the film is dedicated, and there's a "based on real events" note in place of the usual disclaimer. It's been described as depicting how Davidson's life might have turned out without comedy as a career.

Scott Carlin (Davidson), 24, is still devastated by the loss of his firefighter father when he was a child. The depressed high school dropout suffers from Crohn's disease and ADHD. He is also an inking aficionado who talks vaguely of opening a combination tattoo parlour-restaurant.

But Scott lacks direction and motivation: he's unemployed and spends most of his time smoking marijuana and hanging out with his friends. He and Kelsey (Bel Powley) are in a clandestine and not-very-serious (from his perspective) relationship.

Scott's mother Margie (Marisa Tomei), an emergency room nurse, and younger sister Claire (Maude Apatow) - who's graduated from high school and entered college - alternate between frustration over and concern over him.

Scott's friends no longer let him practise tattooing on them. When a young kid approaches while the gang is hanging out on a beach and requests a tattoo, Scott's attempt to oblige sets in motion events that provide major upheaval.

This film is Apatow's first as director since Trainwreck (2015), in which Davidson had a small role.

Earlier Apatow-directed films like Knocked Up and The 40 Year Old Virgin were lighter in tone: they were comedies with some dramatic and heartwarming elements.

The look and feeling here seem deliberately less polished. This is a darker and more downbeat film than those earlier efforts. It's not surprising: having a baby and losing one's virginity are more ripe with comic possibilities than the difficult, messy process of dealing with long-term grief and depression.

The King of Staten Island struggles to maintain a consistent tone and focus, sometimes harking back to Apatow's more comedic efforts, but more often feeling like a drama with occasional humour. And the film suffers from a not uncommon Apatow flaw: overlength.

It begins with sequences that feel almost documentary-like at times but after Margie meets the little boy's enraged father (Bill Burr), the film starts taking some turns that feel contrived to keep the story going in the desired direction.

Davidson is a distinctive screen presence, tall and gangly and big-eyed and shambling and sharp-tongued but also radiating vulnerability.

The King of Staten Island certainly won't be for everyone. But it ends on a hopeful, if not very resolved, note and like its main character, it's strangely likeable and compelling despite its flaws.