Rage, Sally Potter, 95 mins (15)

Up close and really rather fabulous: Sally Potter pares everything back to basics with a talking-head snapshot of the fashion world that fails to offer new insights but still captivates

A film is a film is a film, you'd think. But it's strange how context can make a difference. When Sally Potter's Rage screened in competition in Berlin in February, it generally got the critical thumbs-down. Perhaps it wasn't what people expected: with its prestige cast (Steve Buscemi, Judi Dench, Eddie Izzard, et al), we seemed to be in for a racy ensemble drama about the fashion industry.

But there was no ensemble to it – every performer acted alone – and no ritzy frocks, apart from those worn by Jude Law. We got a succession of monologues to camera, each actor framed in close-up against flat backgrounds in colours ranging from sober steel grey to screaming yellow. The effect, on the Berlinale Palast's huge screen, was overpowering to say the least.

This week Rage reappears in a different, rather peculiar context: in a set of simultaneous premieres across the UK, plus a release on mobile phones. Having seen it on the big screen and on my laptop, I'd be curious to see how Eddie Izzard looks smirking at you from an iPhone. This is an intriguing release for a director who has never taken the conventional route. A fixture of British film's experimental wing (such as it is) since the late 1970s, Potter has always been adventurous, and only sometimes as cerebral as her reputation suggests. Her Orlando (1992) proposed a cool but sumptuous imagining of Virginia Woolf, while her last film, Yes, was a political romance about the global condition – in iambic pentameter.

In Rage, Potter pares everything down to DIY basics. Backstage at a New York fashion show, assorted characters are filmed by a teenager named Michelangelo, who's quizzing them for his web project. All his interviewees choose, however improbably, to confide in him – from overlord financier "Tiny" Diamonds (Izzard), through PRs and scheming interns, down to the underpaid seamstress (Adriana Barraza) and hapless pizza delivery man Vijay (Riz Ahmed).

At some point in the narrative – itself as skeletal as a superwaif – two models come a cropper and a police investigation begins. Meanwhile, a protesting crowd rumbles offscreen – a portent of apocalypse both for Diamonds' fashion house and for Western consumerism.

As a serious critique of the fashion world, Potter's script offers little insight or subtlety. The characters expound views that come across as either transparently, deludedly self-serving or as sweepingly sloganistic: Dench's grandly sour critic declares, "Fashion's not an art form – if it's anything at all, it's pornography." Taken together, Potter's discursive mosaic provokes no novel conclusions: so the fashion world, despite producing occasional marvels, is exploitative, hollow, damaging to women and full of creeps. Who knew? We learn much less here than in The Devil Wears Prada, or even Zoolander, and as for the conflation of fashion and apocalypse, there's a decided after-whiff of Bret Easton Ellis's Glamorama.

But cinema isn't necessarily any more about text than fashion is. Where Rage impresses is as portraiture: not so much of its broadly cartooned social types, though some are vividly entertaining, as of the actors themselves, their faces and mannerisms. Simon Abkarian overdoes it joyously in piratical hat and piratical whiskers à la John Galliano, emoting operatically as designer Merlin ("I am an event!"). Bob Balaban is superbly passive-aggressive as a weasly PR man, and Judi Dench, set against intense fuchsia, is magnificently spiky, spitting contemptuous aperçus and lighting a spliff from a handy little pistol.

The novelty turn is Jude Law cross-dressing as supermodel Minx, sporting a series of preposterous wigs and an intermittent Russian accent (is Minx from Minsk?). All flirty grandeur ("Are you shy because I am celebrity, yes?"), it's Law's most theatrical screen performance yet, but it's perfect here, both a larky send-up of his own beauty and a comment on the catwalk model as imaginary woman.

But the people most redolent of the flesh-and-blood humanity that fashion operates to obscure are Steve Buscemi and British model Lily Cole. Buscemi, as a burned-out war photographer reassigned to the combat zone of the catwalks, is virtually a memento mori with his scrawny chicken neck, freaked eyes popping from those insect features: he's never been photographed so unnervingly. At the other end of the spectrum is Cole, as ingénue Lettuce Leaf: despite a variety of wigs, there's no disguising the irreducible strangeness of that Martian-mermaid face ballooning across the screen in extreme close-up. And Cole proves she can act, to poignant effect.

You wouldn't think that a film that essentially parades faces in close-up for 95 minutes could hold the attention, but I found Rage consistently more compelling than Abbas Kiarostami's recent, somewhat reverent Shirin. There's also the work that Potter and director of photography Steven Fierberg do with colour, with eyes digitally retouched to match the backgrounds: most bizarrely when Vijay, painted blue from head to foot, is shot against a pink that rhymes with his bloodshot eyes.

While this may not be entirely what Potter intended, Rage makes most sense if you approach it not as a film but as a piece of intensely stylised video art. I don't mean to suggest that Rage is hollow but handsome – and yet if it were, what neater ironic comment on the glamour that it satirises? As drama and critique, Potter's creation is not nearly mordant enough. But as a purely plastic creation, an unusually sensuous essay in cinema povera, Rage is oddly compelling, a genuine one-off.