Going to a screening of Michael Moore's Sicko last week, I was in two minds - does the world really need another Moore "shockumentary"? What was I going to learn other than that in America, you pay?

A bit more than that, as it turns out. In Sicko, Moore puts the US health care system under the microscope. His main attack is on the country's Health Maintenance Organisations (HMOs), and the willingness of those on Capitol Hill to hand over the reins to the Insurance and Pharmaceutical industries. It's clear the system is rotten, he says, and must be overhauled.

As a British viewer attending a London screening, I was first struck by how forcibly the film was tailored to a US audience. Understandable, perhaps - after all the stated aim is to initiate a popular movement to change the system. But what Moore has also made is a global blockbuster, at the end of which, I was both unclear as to what exactly was to happen next, and uncomfortably aware of the patronising anti-americanism it could so easily provoke.

As the film progresses, Moore argues that the real problem is with "Us", "Us" being the Great American Public. What has happened to our great nation, he asks? Why aren't we more like the French, demonstrating at the drop of hat? Or the Brits, who would (according to Tony Benn) rise up in revolution if anyone laid a finger on the NHS, or even (gasp) the Canadians, our slightly dopey, but nevertheless healthy, northern neighbours?

He hasn't lost faith in the American character though, he sees this apparent apathy as a result of the isolationism and culture of fear inculcated by the present adminstration. The problem is this; Americans have been scared witless by a greedy government only interested in lining its own pockets, and using McCarthy-esque tactics to generate popular opposition to "socialised medicine". People need to open their eyes. And Sicko is going to help them do it.

He embarks on a glory tour of foreign health services, interviewing some polite Canadians just over the border who never have to wait more than 45minutes for a hospital appointment. Passing through London he chooses Tony Benn and a good-looking audi-driving young GP at Hammersmith hospital to represent the wonders of our own national health service. Moving on to Paris he has dinner with some enormously self-satisfied American ex-pats and accompanies a fatherly house-doctor driving a Nissan around the nighttime Parisian streets. Finally, and inevitably, he ends up in Havana, with a group of 9/11 rescue-workers who are dutifully cared for by some of Cuba's world-renowned health workers.

What is deeply frustrating about much of this aspect of the film is what Moore knowingly and deliberately omits. He does not have to work hard to expose the horrors of the present US system - doctors incentivised to deny treatment, the enormously inflated cost of medication, and an unchecked insurance industry. There are heartbreaking personal testimonies - the insured couple bankrupted through a series of serious illnesses, the widow whose husband was refused treatment on "experimental" grounds, the uninsured man forced to choose which finger to reattach after a carpentary accident. (A sentimentalist, notes Moore, he opted for his ring finger.) But the biased portraits of the alternatives undercuts much of the impact of this footage.

As a Briton, yes I absolutely assume my right of access to free healthcare, but equally i have seen and heard countless horror stories of the NHS; MRSA, enormous waiting lists, doctor shortages, hospitals closing... It's in the news every day. And how, i wonder, is one London hospital indicative of the state of an entire national service. Moore would perhaps have been better to visit a rural or regional community. I'm sure people still would have laughed in embarrassment as he asked "how much did that baby cost" in a maternity ward, but he may have been able to present a more rounded view of a deeply troubled system.

Nevertheless, Moore's great skill is to make mass-appeal films on serious topics. He gives the audience enough comedy to make the documentary go down. Cheap laughs, courtesy, of George W Bush are intercut with moving personal testimonies and shocking real-life footage.

Sicko, overall, is less "Michael Moore" than his previous films, yet he still can't resist opening the film with a typical Bush gaffe, drafting in 9/11 and the war on terror, and laughing at the government's fear of Fidel Castro. He is still virulently anti-Bush, anti-Republican, but "they're human too". Personally, I felt if he had managed to cut these easy targets the film would have been more successful as a result. So, does the world really need Sicko? In the end, yes. If nothing else, it brings to the attention of millions the reality of a broken system, and the need for action now.

Related links: report your health horror stories and read others' experiences in the "USofIll"