This is simply an astonishing film from Herzog. For those who are familiar with Herzog, he has once again found a character - in this case Dieter Dengler - who becomes more and more fascinating upon closer examination. Herzog's films always have the sense of being impressionistic -- he throws the images up on the screen, and they may not always follow each other in a linear fashion, but they nearly always have a sustained, cumulative effect that, by the end of the film, is deeply emotional and troubling.
In this film, the good natured subject starts talking at the beginning and never stops -- Herzog has found someone perhaps even more voluble than he is -- and the audience is perfectly set up by his cheerful good naturedness and lucid observations, because by the end of the film we discover just how unimaginably damaged this person has been by life. The unfolding final images of the film are completely striking in the usual Herzogian sense (if you've seen something like "Lessons of Darkness" you'll have some sense of what to expect), but the meaning is ambiguous: is this a kind of heaven for little boys that love to fly? Or is this a hi-tech graveyard ...
Like Herzog's best (e.g. Even Dwarves, Aguirre, Nosferatu, Lessons and My Best Fiend), you simply cannot take your eyes off this movie.