Synecdoche, New York, London Film Festival

The highly anticipated directorial debut of Charlie Kaufman, Synecdoche, New York is unquestionably the most ambitious American film of the year. Depending on taste, you might also think that it's the most pretentious, but then Kaufman isn't a one-off for no reason.

With his name already an adjective in critical theory, the man behind the fiercely original screenplays for Spike Jonze's Being John Malkovich and Adaptation has produced something from behind the camera that's very, well, "Kaufmanesque".

From its title to its onion-like layers of meaning, Synecdoche, New York is a grand statement on life, art, death and ageing by a film-maker who has just turned 50. At its core is Caden Cotard (Philip Seymour Hoffman), a hypochondriac theatre director living in the New York borough of Schenectady but rushing headlong into a mid-life crisis. As his partner, artist Adele (Catherine Keener), takes their daughter with her to a gallery opening in Berlin, Caden is dogged by a series of repulsive physical complaints, rotting gums and all.

So self-absorbed is Caden, he barely notices the attentions of Samantha Morton's box-office worker, Hazel. Instead, he dives into his work. In a hangar, he embarks on building a scale-recreation of Manhattan, complete with actors playing its inhabitants. An idea that suggests Kaufman's been playing too much Grand Theft Auto IV, which digitally attempted to recreate the same experience, Caden becomes increasingly obsessed with his life's work as the film skips through the years.

It's at this point that life overlaps with art to an almost unfathomable degree. The second half of the film is as daring as it is difficult. Blurring the lines of fiction and reality so much it makes your eyes hurt, Tom Noonan, Emily Watson and Michelle Williams play actors cast by Caden in his masterwork to play versions of himself, Hazel and Adele. By the end, it becomes impossible to tell what is real and what is not.

Difficult to enjoy, frequently feeling like an intellectual exercise, this may be why the film has yet to find UK distribution. Yet for all its wilful obscurity, there are some delightful touches, and Kaufman's fingerprints are all over it. He surrounds himself with class: the cast are uniformly excellent, providing the script with emotional resonance, while Fred Elmes, the cinematographer behind David Lynch's Blue Velvet and Eraserhead, and the quirky composer Jon Brion are valuable additions.

Kaufman can be justly proud that he is now not only the most idiosyncratic writer but also director working today.