Gol is serving more and more regular routes in Brazil. It is starting to expand in the MercoSul as well. But the low cost aspect is all relative: some of their tariffs can exceed TAM´s. Still efficient checking / boarding procedures are still worth the interest and so are the relatively new 737 operated. The only negative point really would be the snacks provided: cereal bars on all domestic legs. Don´t forget to bring your own sandwiches if your flight makes several stop-over.