Are we there yet? Are we there yet? Are we there yet? But that’s the thing isn’t it? There is no “there” in Jack Kerouac’s famous 1957 book about his endless quest for adventure, decadence, and transcendence in late forties America. It’s that lack of a beginning, a middle and an end that has seen off several attempts at movie adaptations before (Kerouac once wrote to Marlon Brando begging him to make it in the late 50s) so kudos to Walter Salles, the Brazillian director of The Motorcycle Diaries, for bringing the largely un-filmable to the screen.

Whatever about plot, the book doesn’t lack strong characters and the prospect of Sam Riley (Sal Paradise/Kerouac), Garreth Hedlund (Dean Moriarty/Neal Cassady), and Kristen Stewart (MaryLou/LuAnne Henderson) playing fictionalised versions of Kerouac’s Beat Generation players is a tantalising one.

Kerouac famously bashed out his tale of pre-hippy peregrinations in one long scroll of teletype paper and Salles’ road movie to end all road movie has a similar stream of consciousness feel. It also looks great with a brilliant attention to late 1940s' period detail but apart from the obvious audience of curious Kerouac devotees, it’s the casting of Stewart as sexually-liberated teen MaryLou that may pique most interest for viewers. Can she, like RPatz before her, make the transition from vacuous teen franchise to something more substantial?

Well, no. She certainly leaves abstinence well behind her and goes from Twilight to threesome in On The Road but her listless portrayal of the 16-year-old wife of ex-con Moriarty is the least of this movie’s problems - it may be Hedlund himself in the central character of wannabe writer Moriarty. He plays the part of the devil-may-care bohemian sensualist with gusto but he is ultimately a womanising, egotistical bore.

Much better is Sam Riley (who was mesmerising as Ian Curtis in Control and less so as Pinkie in Rowan Joffe's misfiring Brighton Rock). He plays our narrator Sal Paradise, a slightly sad, watchful presence who is both intimidated and intrigued by Dean. When the pair hook up, we see them behaving like well-read hoods as they experiment with drugs, hotwire cars, and head up to Harlem’s jazz clubs.

Through a fug of hash smoke in seedy rooms, Sal, Dean and their boho chums wax poetic or spout hardboiled intellectualism like Hemingway on crack. This might be fun when you’re sitting around in a fug of hash smoke but it sure is boring on film. As Carlo Marx (the young Allen Ginsberg), Tom Sturridge is particularly irksome; half in love with easeful death, he torments himself with his longing for Moriarty and announces things like “melancholia is so languorous!” while tugging on another reefer and clasping a Proust novel.

When Sal, Moriarty and MaryLou finally hit the road we are at least treated to some stunning scenery set to the superb jazz music of the day and there are some ravishing shots of the endless highway shimmering off into the distance. We also come into contact with mavericks and oddballs as the trio crisscross the country, not least Viggo Mortensen, looking uncannily like Harry Dean Stanton, playing against type as the eccentric Old Bull Lee (Beat grandaddy William Burroughs).

There is a strange and funny interlude in a motel involving Steve Buscemi and Kirsten Dunst lights up the screen when she flits in and out of the open-ended narrative as Moriarty’s neglected wife. There’s also a very nice turn by Elisabeth Moss of Mad Men fame as a straight-laced matronly young girl who is scandalised by all this free living. Strangely, she’s the most attractive character in the whole film.

However, as the landscape rolls by and Moriarity becomes more intolerable with every mile, you may enter a Zen-state of heightened boredom as the tale of these wandering bohemian bums goes on and on and on. And given the vast setting, it is a strangely muted and constrained take on a novel that sparkles with wildness and unpredictability. The view here is mainly of collective navels.

Kerouac’s book is a sacred text for teenagers and, indeed, anybody who dreams of striking out into the great blue yonder and while Salles’ movie strives for a languid sense of solipsism and self-discovery, On The Road breaks the cardinal rule of an epic road trip – it’s overlong and boring.

Alan Corr