Annie Proulx’s short story Brokeback Mountain was first published in 1997 in the New Yorker. Larry McMurtry and Diana Ossana’s screenplay had been hanging around Hollywood pretty much ever since. It’s not unusual for a film to take years to come into being, but in the case of Brokeback Mountain it would seem to be the ‘difficult’ subject matter which has given so many executives pause for thought. It’s a gay Western, in which two ranch-hands, Ennis Del Mar (played by Heath Ledger) and Jack Twist (Jake Gyllenhaal), working one summer in the 1960s on the eponymous mountain, fall in love. We follow what happens to them over the next twenty years, as they lose themselves in the trappings of convention (wives, kids) and grapple with their feelings for each other. It’s a very moving short story, an illustration of how so many gay relationships have failed to work, and it’s ripe for turning into a movie.

Unfortunately, the movie which director Ang Lee has turned out falls well short of what one would hope for from a ‘gay Western’, let alone a love story, gay or otherwise. As with Jonathan Demme’s Philadelphia in 1994, there’s a regrettable sense that Hollywood wishes to congratulate itself for its daring. And so the first thirty minutes of Brokeback Mountain have that ominous feeling that its characters are headed for something major, and probably not very nice – like the buddies in The Deer Hunter, before they go off to war, or the students in The Blair Witch Project, before they go down to the woods. Sure enough, the time comes for Jack Twist to launch himself at Ennis Del Mar one night in the tent, and lo and behold, we have two young, and pretty buff, Hollywood actors kissing and humping onscreen. What the movie fails to convey, though, is the strength of the two men’s feelings for each other, so that we find ourselves wondering, as they grow into middle age and all the disappointment life brings, what they are really missing out on after all.

Proulx’s prose conveys this very well. Her language is spare, her story brief (you can read the book in less time than it takes to watch the movie) but every sentence tells us – screams to us – that these men should be together, that they want to be together, but that they can’t be. The storytelling is raw and realistic, and what comes across is real human emotion, capped by a last line which speaks to every gay man and woman. In an example of this movie’s clumsy adaptation, that last line is turned into dialogue and spoken by Ledger’s character to Jack Twist – which totally misses the point: Proulx’s observation is more articulate and all-seeing than either character is able to be, and the film has failed to replicate such authorial lucidity for the screen. Instead, it gives us a simulacrum of the story: for those who have read the book, all the details are present and correct – but none of them much matters.

More surprisingly, the film even misses the easy targets hit by the likes of Brief Encounter and The Bridges of Madison County – emotional, if straightforward, stories of missed chances, of love hampered by convention and reserved natures. If nothing else, they tap into that universal sense of a sad ending often being far more romantic than a happy one. Brokeback Mountain , though, falls between two stools: it is neither general enough to appeal as a universal love story nor specific enough to do justice to, and dignify, the monumental struggle of millions of gay men over the years – cowboys and civilians in general.

Regrettably, it’s what passes for a classy product these days, and Ang Lee is what passes for a top-drawer director: an artist’s eye allied to a crowd-pleasing storytelling skill. There’s no doubting his sincerity, his liberalism, and his patience. But time and again his understatement has gone too far, so that he ends up not as a transcendental minimalist but as a rabbit caught in the headlights of his own reputation – The Ice Storm and Crouching Tiger, Hidden Dragon, for example, are two of the most bafflingly overrated movies of the past few years. And if Sense and Sensibility worked, that may be because of Emma Thompson’s triumphant adaptation and her wonderful bottled-up performance.

But all Ang Lee films have their virtues, and Brokeback Mountain follows suit. So, the cinematography (by Rodrigo Prieto) is as clear as spring water, Gustavo Santaolalla’s music tastefully plucks strings of ponderous prettiness, the sheep look terrific, and the actors can’t really be faulted – Ledger does tortured and introspective very well, Gyllenhaal, as Jack, is understandably frustrated in the ‘Martha’ role, and Anne Hathaway and Michelle Williams, as the women sidelined even while being centre-stage in their universes, are fine.

And, of course, it’s great that we have a gay western (outside of Andy Warhol’s Lonesome Cowboys), and in the multiplexes, too – event films like this are all steps in the right direction. But let’s not mistake this daring accomplishment for a good film.

Brokeback Mountain is out in the UK on 06/01