As a device for a film it's interesting to a point -- but it didn't fully work its magic on me.

The Amazing Johnathan Documentary starts as a blast but as the journey progresses, becomes ever more slippery: Is Szeles tricking Berman? Is Berman bamboozling us? The answer is entertaining and frustrating in equal measures.

It's compelling stuff: funny, moving and, yes, often amazing. Johnathan is a slippery subject, but in Berman he has a committed chronicler, who is even prepared to smoke meth with him on camera.

Learning more about Berman's childhood and problems faced completing the documentary just isn't that interesting, and once you see through the illusion, the magic quickly starts to fade.