A FILM about a genius can rarely hope to be as smart as its lead character. But Gus Van Sant's Good Will Hunting (15) has a brave try - and when it runs out of cleverness, it makes such an effective appeal to your tear-ducts that you barely notice you've been fobbed off with sentimental platitudes.

The rosy-cheeked, Bruce Weber Boy Scout-ish Matt Damon stars as Will, a troubled boy prodigy with a Polaroid memory. By day he buffs the lino of the Massachusetts Institute of Technology; by night he cracks complex equations, humiliates preppy know-alls and cultivates his criminal record by getting into fist-fights.

When his talents are noticed by an ambitious MIT professor (Stellan Skarsgard), Will is about to begin a spell in jail. The boy gets bail on the condition that he applies his uncanny talents to cutting-edge maths and pays weekly visits to touchy-feely psychiatrist Sean (Robin Williams). Analyst and analysand concoct a quirkily touching relationship, and Will develops a romance with a brilliant student, Skylar (a superb, unusually natural performance by Minnie Driver).

David Hockney once said of WH Auden, "If that's his face, what can his scrotum look like?" Something like Robin Williams, possibly. Wrinkled, grizzled and a bit loose at the seams, Williams twinkles beneath a forest of laughter-lines and facial hair. If you sheared him, you could probably make a doormat for every household in America. And on it would be written, "Do what's in your heart, kid," in large, friendly letters. This is Williams on-message and restrained, his instinct for mugging and gabbling strapped firmly down.

Van Sant is also on his best behaviour. Apart from the presence of clean- limbed young men, there's little in this film that betrays his hand. A brief slide into slo-mo here, a flash of video footage there, but none of the jumps into iambic pentameter or Super-8 that we've come to expect.

The odd provenance of Good Will Hunting explains both its strengths and its weaknesses. It began life as a short story written for a college project by Matt Damon, who then developed it into a screenplay with his old schoolfriend Ben Affleck (who also co-stars as Will's best mate, Chuckie). The script was then picked up by entertainment giants Miramax. The finished film bears evidence of this process: the script is fiercely witty, and serious in its aspiration to emotional and thematic cogency. But studio production has necessitated a huge injection of weapons-grade Hollywood schmaltz. Shamelessly sentimental Americana toughened up with sly slacker cynicism is a pretty devastating combination, the sort of secret formula that gets the Academy whooping. And it knocked me for six, too. It's only towards the conclusion, when narrative strands get resolved by hugging, blubbing and the surging strings of Danny Elfman's cheesy score, that the alliance between indie and studio begins to feel a little unholy.

The rest of this week's releases are a patchy collection of cross-generic adaptations. Bent (18) is scripted by Martin Sherman from his landmark play about two gay victims of the Holocaust. It's a film of two halves: the first drums up a circus of fishnet decadence presided over by Mick Jagger's faux-Dietrich drag empress; the second is a Beckettian two-hander played out behind the electrified barbed wire of Dachau. Director Sean Mathias makes better work of the latter. His concentration camp is represented by a series of extraordinary post-industrial locations - huge silos strewn with cracked cement; vertiginous gantries; stretches of arid, alkaline waste ground. It's the perfect backdrop to the Sisyphean task set for his protagonists. Max (Clive Owen, rather chunky for a starving prisoner) and Horst (a lean, nervy Lothaire Bluteau) have been ordered to haul rubble from one side of a yard to the other, then back again, ad infinitum. Mathias handles the stark abstraction of these scenes with certitude; but you rarely forget that their power is on loan from the theatre, where they were conveyed with considerably greater impact.

At least two of my colleagues fell asleep during Marleen Gorris's Mrs Dalloway (PG). This, I feel, was an extreme response, but not a completely invalid one. In searching for an apt analogue to Virginia Woolf's fluid narrative structure, Gorris and her screenwriter Eileen Atkins have produced an enervated and discontinuous version of standard Brit-lit costume drama. As Woolf's stylisms were derived in part from early film techniques, it's frustrating that Gorris's take on the novel isn't more cinematic. Instead, she galumphs between three competing scenarios: Vanessa Redgrave's Clarissa Dalloway somnambulating in immaculate Bloomsbury interiors; Rupert Graves's shellshocked soldier going ga-ga in St James's Park; Natascha McElhone's young Clarissa overacting her way through a hackneyed nostalgia of sunlit lawns, linen suits and extras declaring, "Roll on the Glorious Twelfth!" Perversely, the film only comes to life once it has abandoned its attempts at formal innovation to indulge in straightish scenes of vinegary upper-class bitching. Otherwise, it's like a Merchant-Ivory quota quickie to which the Dalloways' gardener has taken his secateurs.

If, like me, you love eavesdropping on other people's arguments, you'll certainly get a kick out of Cedric Klapisch's Un Air de famille (15), a caustic comedy of failure, vanity and sibling rivalry set in a flybown cafe in suburban France. Screenwriters Agnes Jaoui and Jean-Pierre Bacri (who also take two of the lead roles) have made little attempt to transform their original stage play into anything distinctively filmic, but unlike in the case of Mrs Dalloway, this feels like the right decision. Their ear for the rhythm of a family row is pitch-perfect, their ensemble acting witty and well-observed. All Klapisch has to do is to point the camera at whoever's talking - and as he's using a widescreen format, he's able to stay as static as Caruso, the arthritic family dog who sits on a cushion by the bar. Nothing swish, nothing fussy: just a smart play, simply photographed.

Which makes it a very different experience from Middleton's Changeling (18), a well-meaning but technically cack-handed attempt to do for Jacobean revenge tragedy what William Shakespeare's Romeo +Juliet did for the Bard. Unfortunately, with his focus firmly on gore-spattered bosoms, director Marcus Thompson's sensibility seems closer to that of Jesus Franco (he of Vampiros Lesbos notoriety) than Baz Luhrmann. And the performances don't raise the tone. Billy Connolly makes a couple of baffled appearances that fail to justify his prominence in the billing. Amanda Ray-King plays tragic heroine Beatrice-Joanna with the monotone woodenness of a two-bit porn starlet who's blagged her way into a legit movie. And performance- poet John Cooper-Clarke has a guest spot as inexplicably irrelevant as any celebrity cameo in an Ed Wood film. But this is thick-eared exploitation film-making at its most cheerfully crude, and Thomas Middleton may well have got a kick out of its blood-soaked, lo-fi bravado.

Lastly, a plea to Hollywood to make my life less predictable. A fortnight ago I saw Brian Cox as a no-nonsense IRA man clashing with an amateur boxing coach. Last week I saw Brian Cox as a no-nonsense police chief on the trail of a twisted serial killer - with a glamorous doctor as the love interest. In this week's Kiss the Girls (18), I saw Brian Cox as a no-nonsense police chief who teams up with a psychologist-cum-amateur boxing coach (Morgan Freeman) to go on the trail of a twisted serial killer - with a glamorous doctor as the love interest. But Gary Fleder's routine thriller inspires a vague sense of nausea as well as weary deja vu. The script - adapted by David Klass from James Patterson's novel - is an undistinguished round of starlet-slicing that tries to assuage its misogyny by including a scene in which the detectives deduce that the killer is only preying on "strong-willed, defiant women". You don't have to be a genius to spot the irony.

Cinema details: Going Out, page 10.