It is great to have that kind of place for artists do their magic :)
Don't appreciate when there is graffiti or tags in places where it's not supposted to be.
Back to the festival, this year it was around 100 artist from all over the world transforming the walls, and around 10 000 people was there to see it this year (its growing each year!). There was not only graffiti but foodtrucks and music in the evenings, so its worth to go there and see it all.
I was there just before they opened in the mornings, that's why there is few people in the pics :))