This is the cinema-release version of a PBS documentary which originally ran at over three hours: an intimate, affectionate and warmly celebratory study of the great comedian and film-maker Woody Allen, directed by Robert B Weide, a documentary-maker who has also directed Larry David's Curb Your Enthusiasm. It has fascinating behind-the-scenes footage of Allen directing on location, in the studio, working in the edit suite, and also glorious material on Woody's boyhood and early life that is as compelling as a Philip Roth novel. I watched this engaging film with a great big smile on my face. I don't think anyone with any love for Allen, or the cinema, could fail to do anything else. To see him scribbling scripts on his yellow legal pads or hammering them out on a typewriter that he has had since a teenager is almost awe-inspiring. There can't be a life story in postwar American cinema more inspiring than his: the comic genius who started out as a gag-writer for the newspapers, then a standup, and then a film-maker who insisted on auteur prerogative without ever needing to use the word, and who became an evangelist for the masters of European cinema.

Having said all this, Weide shows a loss of nerve in declining to engage much with the great Soon-Yi scandal, the awful moment in 1992 when Woody Allen was found to be having an affair with the adopted daughter of his partner Mia Farrow; a sensation that caused a karmic trauma after which, it could be said, his work lost ground. The affair could explain his ceaseless industry and return to undemanding comedy; but Weide does not care to discuss these issues. Soon-Yi is discussed very gingerly, cursorily; there's a montage of the tabloid front pages, and Allen blandly says that people are entitled to whatever opinion they like. Really, the question is given a pretty wide berth. Is it the elephant in the living room? Well, Woody Allen may have fallen in love with the wrong woman, but the relationship seems to have been entirely stable since then. Maybe there's no more to be said.

Part of the pleasure of the film is seeing those people who have been legendary names on the credits of movies we have grown up with, people like Jack Rollins, who with the late Charles H Joffe (shown in archive footage) was Woody Allen's manager and then executive producer from the earliest days. Letty Aronson, Allen's sister and his producer from the early 90s, is also interviewed. This documentary is a pleasure, though we don't get too far beneath the surface.