As the title suggests, Chris Waitt's documentary is a confessional - an exercise in navel-gazing that exposes more of his body-parts than is seemly and relies on us finding the 38-year-old Brit interesting for an hour-and-a-half. He's in search of exgirlfriends who can explain why they dumped him. At one point, he's simply in search of sex (in Leicester Square, at two o'clock in the morning). His quest is gimmicky, contrived and intrusive. Yet it's also one of the most enjoyable films of the year.

Blonde, tousle-haired Waitt boasts a range of little-boy-lost expressions that Nick Broomfield and Louis Theroux would envy. But the man he's closest to in spirit is Woody Allen. Like Allen, Waitt's schtick allows him to play both loser and louse. Like Allen, he has an eye and ear for "real" women who see through his act. Think of History as a no-budget Manhattan.

Documentaries, just like feature films, need a charismatic cast and Waitt's ex-girlfriends fit the bill. There's politely angry Olivia, sexaddict Danielle, laid-back Za and - most important of all - Vicki.

Attractive, articulate, unusual, these women are natural-born stars.

Of course, it takes a while for him to get them in front of the camera and Waitt milks as many laughs as he can from his failure to even get them to talk about his failures. The majority put the phone down. He finally gets one to talk, which is when we get our first hint that Waitt is more complex than he seems.

Dawn dumped Chris when he tried to kiss her mum. Now pay attention: mothers are a theme here! His mother is important. So are his girlfriends' mothers, and his girlfriends themselves when they get pregnant. Chris loves mothers. What's slowly, and very subtly, revealed is that he can't cope with the idea of being a father.

History is a dishonest film about the need for honesty. Za tells us she worried about Waitt's mental health and she's not joking: he used to think he was Jesus Christ. Vicki ... well, I won't spoil the surprise but her tears provide a very different kind of shock. Scriptwriters are always told to write about what they know. Waitt talks to women he knows and because 1) they're prepared to open up and 2) he's a canny film-maker, by the end we find ourselves thinking about big issues - madness, sex, parenthood - in a new way. Low-budget British films often exploit their own status as "underdogs". Here's one that truly deserves to be a success.