This show couldn't fail with the talent that's involved, and in parts it is really great. The Os Gemeos, Barry McGee and Steve Powers sections stood out for me. Banksy's section is good; it's great to see the classic stencils mixed in with newer pieces (for me it's really special to see the simple stencils that first got me into street art in London - 'Buried treasure' and 'This is not a photo opportunity'). This show will go down as an important event, and it will help broaden recognition of street art.
But Art in the Streets is a missed opportunity: the show focuses so heavily on graffiti that it ignores so many of the important street artists that have been active in the last 10 years, without whom this show would not have happened. The 'street art movement' of the last 10 years is minimally represented; of the hundreds of artists that have appeared on Unurth, only about 12 are represented in this show (of ~95 total). Some people say that's necessary to give a historical perspective; but it's hard to make that case when the most important influence (Blek le Rat) on the most acclaimed artist in the show (Banksy) is absent.
And the Blu debacle matters; the show is much poorer for his absence, and the spirit that he represents.
The Banksy gallery:
Shepard Fairey, Neckface, Kaws, Swoon, Andre, Retna
Keith Haring, John Fekner, Steve Powers/ ESPO, Barry McGee, Amaze, Futura
Roa, Space Invader
MOCA's information on the show.