Michael Haneke is too good. Whenever the Austrian director shows one of his films in Cannes, I always come out thinking the others might as well just pack up and go home because they'll never reach his awesome heights of control and precision. It's like the days when Beethoven was around and everyone else gave up composing. Haneke's Amour, about an elderly man looking after his frail wife (Jean-Louis Trintignant and Emmanuelle Riva, both utterly captivating) when a stroke confines her to their Paris apartment, was by some stretch the finest film at Cannes. It was the only piece to be exquisitely acted, composed, paced and pitched, as well as addressing vital human themes and drawing a swell of emotion from its viewers. Nothing else came close to ticking all those boxes.

But cinema needs different voices and styles on which to feed, and Cannes 2012 welcomed them all in. This year's Palme d'Or selection – much criticised for not including any films made by women – still managed a startling breadth of subject, quality and genre, and the jury often rewards artistic risk rather than polish.

In which case Leos Carax has a chance for his properly bonkers film Holy Motors. The director of the notorious 1991 French folly Les amants du Pont-Neuf has been away from feature films for more than a decade, and returned at Cannes with the nuttiest offering on display, featuring that wonderful French actor Denis Lavant – part acrobat, part mime artist, part satyr – as Monsieur Oscar, who plays 11 different parts, changing in the back of a white limo as it glides around Paris from one rendezvous to another. He's an old lady begging on a bridge, a dying man, a father picking his daughter up from a party, a motion-capture performer on a green screen, a velvety leprechaun called Monsieur Merde who flits through Père Lachaise cemetery and interrupts a fashion shoot to kidnap the model (Eva Mendes), lick her armpits and eat her hair. (You don't get that in a Ken Loach.) When Oscar meets Kylie Minogue in the deserted department store La Samaritaine, she bursts, Demy-style, into song before dangling perilously off the building's roof.

What does it all mean? I'm not sure. Something to do with the faces we present, the games we play, the different parts we have to act in life before we can come home and be ourselves? Holy Motors is playful, daring and fun to watch but not, in the end, moving. It does contain my standout moment of this year's Cannes: a sweeping travelling shot through a church as the extraordinary Lavant joins a marching accordion band for a rousing oompah number. It's probably too "out there" for a jury run by Italy's Nanni Moretti and containing Ewan McGregor, Diane Kruger and Alexander Payne, but the loopiness of Holy Motors was very welcome, if only to get people arguing.

After a good start, the festival became a little lazy in the mid-section, with former winners and favourites doodling. Abbas Kiarostami with Like Someone in Love, Hong Sang-soo's In Another Country, Alain Resnais with You Ain't Seen Nothin' Yet and even Ken Loach. His latest and record-breaking 11th Cannes entry was The Angels' Share, a perfectly likable comedy about the redemptive powers of whisky that is also shot through with a social conscience. The fact that it was so warmly received here indicated to me that everyone was desperate for a laugh.

Maybe the most frustrating film was the one I was most looking forward to: an adaptation of On the Road by the Brazilian director Walter Salles, whose road movie The Motorcycle Diaries was so lovely back in 2004. I was heartened in advance to see he'd even re-formed his team of Eric Gautier on camera and Gustavo Santaolalla on music. Here, Sam Riley's Sal and Garrett Hedlund's Dean Moriarty (both attractive enough presences) consume vast amounts of pot and beer, yet never even smile. It's like an American Withnail & I without the laughs. The episodic structure of this handsome, aimless film should have at least allowed for some diverting side roads, but each time a cameoing actor popped in (Amy Adams, Steve Buscemi, Viggo Mortensen, Kirsten Dunst), they were all as gloomy and one-note as each other. And what is it about? Friendship? The creation of a literary icon? Salles, for once, doesn't get to grips with his subject, and the film doesn't throb with his usual intelligent empathy. Even the Charlie Parker bebop fails to enliven proceedings, while Twilight's Kristen Stewart takes the miserable biscuit, pouting away in the passenger seat.

Also set mainly in a car is David Cronenberg's Cosmopolis, as Robert Pattinson is chauffeured around a chaotic, near-future New York in search of meaning and a haircut. It's a violent picture which questions the meaning of violence in terms of financial and societal collapse. This is a chilly, talkative film, heavy on the stylised dialogue ("life is too contemporary"; "the present is hard to find"), and Mr Twilight acquits himself quite well, though like too many young stars here he fails to build his performance throughout the film.

US cinema was given prominence this year, and flickered rather than shone amid displays of highly stylised brutality. Lawless was hokey and unoriginal. Killing Them Softly starred Brad Pitt as a hitman cleaning up after two chancers (well played by Scoot McNairy and Ben Mendelsohn) rob a mobster's gambling den. It's a smart, cold film, with a sub-Tarantino outlook but with flourishes by director Dominik, whose ace is to mirror the financial crisis and the underworld. And James Gandolfini is great as another hitman, wallowing in drunken self-pity.

Lee Daniels's The Paperboy was something else – though it was the third US movie here to feature a character getting his throat slit. It might well be the worst film ever to have shown in competition, but this being Cannes, "trash" films can be considered a genre in themselves and Daniels's wild, lurid piece is ingeniously rubbish. Playing a flirty, cheap blonde obsessed with death row inmates, Nicole Kidman urinates on Zac Efron; meanwhile Matthew McConaughey gets hog-tied and slashed, John Cusack acts nasty, Macy Gray narrates and Daniels, the director of Precious, slaps on another funk soul track on whenever he fancies, like some addled DJ enjoying his own house party.

The potboiler plot is all over the place, but it's still sexy, colourful and ludicrous, while managing to deal with race, homosexuality and murder in late-60s Florida. Although it never really has a sense of fun and burns with ill-focused anger, The Paperboy represents a kind of triumph, surely, even if it's just in getting such high-profile actors to do such low-down deeds.

Danish director Thomas Vinterberg returned to competition 14 years after Festen with a hideously ill-judged film, The Hunt, in which Mads Mikkelsen plays a primary school teacher accused of sexual inappropriateness by one of his pupils. He's hounded out of town in the most hysterical way, but the film is reckless with its logic and fails to observe due processes of plot, milieu, verisimilitude – massive failings when dealing with such a sensitive subject.

One British title to get some real buzz was in the far reaches of the Directors' Fortnight section, where Ben Wheatley's Sightseers offered up a slice of home. After all the romantic mythologising of On the Road's Americana, it was genuinely comforting to watch a film mapping a journey from Redditch through to Shipton, Chesterfield and Ribblehead viaduct. It tells the blackly funny story of a pair of lovers who discover a taste for bumping people off in campsites, like two Sweeney Todds of the caravan set. With a little more script development, Wheatley's worldview and knack for dialogue could make him a real force in UK film, like a hipper Mike Leigh.

But what will win the Palme d'Or tonight? I hope it's Amour, a film that is Haneke's most personal and tender, and yet bristles with threat and fear. It could be In the Fog by Sergei Loznitsa, or Jeff Nichols's Mud, both of which played too late for me to get them into this roundup. If either really is better than Amour, that will be a great film indeed.

And the award for silliest outfit… Jason's alternative gongs

Best comeback news Jean-Luc Godard isn't à bout de souffle yet. He's begun a new film, called Goodbye to Language, and is shooting in 3D.

Best credit Sax consultant, On the Road; dresseur de pigeon, Amour.

Best dressed Actress and jury member Diane Kruger in Balmain; actress Paz Vega hot latina on red carpet for Madagascar 3, though that's really not important.

Best music Rust and Bone; The Paperboy.

Best actress Marion Cotillard, left, for Rust and Bone.

Best couple Jean-Louis Trintignant and Emmanuelle Riva in Amour, Kanye West, right, and Kim Kardashian aboard a yacht.

Best actor Denis Lavant, Holy Motors.

Best actor in captivity Ariello Arena, star of Reality, currently serving a life sentence.

Best opening sequence Moonrise Kingdom.

Best shot Family day out scene at waterpark in Reality.

Best rediscovery

Jazz documentary A Great Day in Harlem (1994) by Jean Bach.

Silliest outfit Jeremy Irons donning fedora, silk scarf, boots and pantaloons to wander round rubbish dumps in Trashed.

Best non-film celeb spot Didier Drogba, swaggering like a winner into lunch on the Nikki Beach rooftop, coolest dude in town.

Best celeb snub Killing Them Softly is Andrew Dominik's second film directing Brad Pitt. So, he must be round Brangelina Mansions for dinner all the time? "Er, no, never been," he told me, clearly just realising the snub. "We've been out to dinner together, me and Brad. Does that count? Actually, I'm not even sure where Brad lives these days."