i thought it was really good, it's a commentary on the art world and how full of shit it can be. it addresses the hype that banksy has gotten by bs celebrities buying his work and it being the cool thing. i could justify more of the movies motive but i dont want to ruin it for people that still want to see it. but yeah, if you dont like banksy, shepard fairey, space invader, or have no respect for street art in general then you will probably hate on this film.
but people saying it's just a collection of footage that has already been seen are wrong, part of the concept of the movie is that it is a collection of footage taken by a frenchman that was able to befriend many of these guys and film them in action.