Oscar-winning director Ang Lee's latest film aims to shine a light on the hypocrisy faced by returning war veterans in America, but it falters in tone and emotional impact.

Based on Ben Fountain's book of the same name, the story focuses on the titular character who has returned home to Texas from a gruelling tour of Iraq in 2004.

The clean-cut, 19-year-old Billy Lynn has become the poster boy of American patriotism after a video of him fighting off an Iraqi insurgent while defending a wounded sergeant went viral.

The soldiers have the dubious honour of being part of a football halftime show

Billy and his Bravo Squad comrades have been granted leave from their duty in Iraq to embark on a victory tour in the US, culminating in an appearance alongside Destiny's Child during the halftime show of the Dallas Cowboys' Thanksgiving game.

The film takes place in one hectic, bewildering day for these reluctant war heroes as they are thrust in front of cameras, ranted at by members of the public and paraded about in front of cheering crowds at the game.

Kristen Stewart overcomes weak dialogue to deliver an impressive performance

All the while, their ceaselessly energetic manager (Chris Tucker) is trying to land them a lucrative movie deal based on their story, and Billy's sister Kathryn (Kristen Stewart), the only anti-Iraq war liberal in the film, is desperately trying to convince him to seek an honourable discharge.

Oh, and shoehorned into the proceedings, there's an awkward and ill-conceived love story between the virginal Billy and pretty young cheerleader Faison (Makenzie Leigh) which plummets proceedings into new levels of cheesiness.

Makenzie Leigh plays Faison, a cheerleader who captures Billy's eye

On the positive side, Lee has successfully managed to depict the huge gulf between the public's perceptions of the soldiers and their feelings on their achievements in Iraq. They grow increasingly uncomfortable with being feted by the public, particularly Billy, who bears the brunt of the attention.

Their war experiences are unveiled gradually through flashbacks, often triggered by loud noises, which reveal the true horror, and perhaps even the futility, of being stationed in Iraq, as well as offering glimpses into the devastating effects of PTSD.

The squad's war experiences are revealed through flashbacks

Newcomer Joe Alwyn gives an impressive performance as Billy, serving up a persuasive combination of boyishness and world weariness, while hinting at suppressed trauma.

Stewart grapples with some particularly galling dialogue as his cynical sister but is still very good, and Garret Hedlund is excellent as the squad's no-nonsense, sarcastic leader. Kudos must be awarded to Steve Martin, too, who has a greasy turn as the Dallas Cowboys' owner, who has echoes of Kevin Spacey's wicked House of Cards president.

Garret Hedlund impresses as the squad leader

Despite the wealth of acting talent on offer, they can do little to rescue the superficial, frequently clunky dialogue, uneven tone and often spectacularly forced scenes of brotherly camaraderie between the soldiers.

The film's downfall could at least in part be due to Lee's decision to push technological boundaries by shooting in an ultra-HD format of 120 frames per second - compared to the usual 24 - despite most cinemas not being equipped to screen this version of the film. The conventional 2D version is the sole iteration that will be shown in Ireland.

You can't help but think that most of the effort and consideration went into achieving this technological feat to the detriment of the narrative.

Sarah McIntyre