I would not call this a comedy. Maybe a tragicomedy. It is true, some scenes are funny. But that's not the point. The point is to give an hyper-realistic, painful portrait of extreme ignorance and poverty, and its consequences. These people cannot afford to be good, honest, or have any positive family feeling. Like prisoners in a Nazi camp, they are deprived of all their humanity. The only thing that keeps the family united is the shack they live in, and the idea of taking Giacinto's money. I want to stress the fact that the movie _is_ realistic. There _were_ shantytowns around Rome in the seventies. And the people _were_ like that. The constantly mocking and jocking attitude is a trait of the Roman popular culture. It does not mean they're happy and light-hearted. So beware, this movie won't just give you a good laugh. If you like it, check this out as well, I don't think you can buy it, but the Italian RAI TV showed it some time ago:
http://us.imdb.com/title/tt0073339/
http://us.imdb.com/title/tt0073339/