I did not attend the mask festival, though I am somewhat familiar with the masks that are a part of the Bwaba culture because of Abdoulaye in Boni, a sculpture and a good friend of FAVL. When I was in Boni for reading camp last year, there was a funeral, and Jonas (the librarian in Boni) took me and the other volunteer to see the masks dancing. People were playing drums and balafones in the background and the masks were dancing in a circle to celebrate the life of the man who'd died. Women (who are not allowed to wear masks) danced in a bigger circle around the masks. The dancing and music went on day and night for four nights, the masks going in shifts. It was really interesting to see, though I've heard that some masks can get violent (they hit people with sticks) and ask people (especially tourists for large sums of money).
A fellow PCV and another friend of FAVL, Scott, did attend the festival and also happens to be an excellent photographer. For absolutely amazing images of FESTIMA 2012, visit Scott's blog.