As a designer, and a fan of graffiti and graffiti-style, I really enjoyed this documentary. It was very interesting to get a "behind the scenes" view of the mindsets behind the bombers and artists, and to see how the philosophies around the world vary.
Like Kizmar mentioned, I don't think Reiss effectively made distictions within the culture enough... while he showed the many facets, it felt he lumped them all together. To me, there is clear distinction between actual urban street artists, bombers, gang taggers, and blatant vandalism.
All said and done, I still think this was fantastic, and it was very intriguing for me to see the motivations of graffiti artists - especially in other countries.