Indeed! Im (besides an ex-professional in advertising, now teatcher in this matters) 100% for clean our cities visually (and literally too), and SP did, IMHO, a huge job on this way... the SP Mayor, G Kassab fought a lot to achieve it and (better!), there are now discussions on my city (Porto Alegre) in order to follow SP example! We have, as SP (Porto Alegre looks very alike to SP, but in size wich is circa of 10% of that huge metropolis), PA has beautiful 30's and 40's Art Nouveau/Dèco buildings today hiden by advertising... I hope soon I can post pics of my renewed city!
I'm an architect student, living in Sao Paulo. Imho, this law is good as a first step to clear the city. But only the first step... Removin' big ads only show us what and why we need to set-up. There are a lot of trashes that need to be banned out and also many traffic/pollution problems.