Like a big budget Blair Witch Project this is a clever and amusing con job that shows the manipulative power of the documentary but as the film becomes more and more preposterous and the con becomes more obvious the joke goes a bit flat.
Lately the documentary genre has been messed with royally with blending opinion and personal agenda with fact mainly for entertainment value ala Michael Moore and Morgan Spurlock's Super Size Me, but this one side steps in yet another direction and seems to me to be satirizing the whole mocumentary process which would make it a joke within a joke and a true original. It's not entirely clear if this is the intent of the film, which only adds to the enigma. I like to think it is.
It is refreshing to see a legend like Herzog willing to poke fun at his own obsessive reputation and it's his charismatic presence that carries the film.
I don't know when the mocumentary first showed up in film but one of the first I recall that's well worth checking out if you like this sort of thing is Woody Allen's great from 1983: Zelig.
