★★★

I spent much of Richard Linklater's Boyhood wondering why I wasn't liking it more. It comes garlanded with tributes from critics and audiences alike and it's a genuine original, put together with care, patience and a lot of chutzpah.

The story of its making has been well covered. Linklater shot it over a span of 12 years, gathering his cast together annually for a series of three- or four-day shoots as he chronicled the childhood and adolescence of his star. Ellar Coltrane was six when fllming began and a high school graduate when it finished. In other words, the film's real star is time itself, a fact that inevitably invites comparisons with Michael Apted's Seven Up series.

But Apted's films, which followed a group of British children as they grew up and into middle age, were documentaries. Linklater's is a fiction – or rather a strange hybrid between the real and the imagined. Milestones in Ellar's life found their way into the script, and the cast successfully eliminates any hint of starshine from their performances. A thoroughly lived-in feeling pervades every scene.

Nonetheless, with Ethan Hawke and Patricia Arquette playing the boy's parents, you're unlikely to surrender to the thought that you're watching real lives unfold. Instead, the film's cinema verite borrowings prove a distraction. The episodic structure is irritating with its odd jumps and elisions, as well as leaving behind one or two nagging questions.

The angel-faced Mason jnr (Ellar) and his nine-year-old sister Samantha (Linklater's daughter, Lorelei), are just becoming re-acquainted with their wayward dad, Mason snr (Hawke), when their mother, Olivia (Arquette), announces they're moving from their small Texan town to Houston so she can study to become a teacher. It's the first of the many moves that will define their upbringing.

Olivia is a smart woman and a loving and conscientious mother but her judgment goes AWOL when it comes to choosing the men in her life. In Houston, she marries Bill, a college professor (Marco Perella) with two children, and for a while all goes well. The families blend and Olivia no longer has to worry about money. Then her new husband reveals himself to be an abusive drunk and once again, she and her children are on the move.

It's a powerful sequence, made all the more so by Linklater's skill in easing you into it. One by one, the warning signs appear in the egregious Bill's false heartiness and macho posturing until he's bringing out the vodka bottle at breakfast time and making the kids' lives miserable with petty and not so petty acts of humiliation.

Once he's out of the picture, however, the action settles into a rhythm so humdrum that the film's air of authenticity fails to be as fascinating as it must be if Linklater's grand, two-and-a-half hour scenario is to work. Ellar proves to be an increasingly endearing character – thoughtful and gentle without being a pushover. He faces down a couple of bullies at yet another new school, using nothing more than self-composure. And Samantha, his sister, is just as engaging as she changes from bouncy kid to capable and confident teenager.

But Hawke's Mason snr shapes up as a predictable presence. Hawke liberates the slacker within to give us a middle-aged Peter Pan who's growing into maturity at about the same pace as his kids, although they keep threatening to overtake him. He's supposed to be charming in a well-meaning way but his languid amiability is so unshakeable that his personality seems stuck on one note.

Arquette is much more watchable. Her Olivia is doggedly ambitious with a life-loving optimism that sustains her through the roughest patches, while tripping her up just when her prospects are at their brightest. She's a poignant figure and Arquette knows her intimately.

But the film's best bits don't give us nearly enough to justify those accolades or dispel the feeling that you're being taken on a leisurely meander through lives short on surprises and revelations. For a real sense of time's Janus-faced qualities as healer and destroyer, it doesn't come anywhere near the Seven Up series. In the right circumstances, fact can trump fiction. Maybe Linklater should have given himself the chance to find out by going all the way.