It was interesting seeing the same waterfalls from two different sides, from within two different national parks covering essentially the same area. The Brazilian side had a long pathway that ran alongside the river, a bit further away from the falls, which allowed for breathtaking views of the entire width of the falls. The Argentinian side had a long pathway that ran alongside some of the falls directly, allowing for up-close views (and photos). We were definitely impressed by both sides of the falls, though my personal favorite was the broader view on the Brazilian side. The entrance fee on the Argentine side was 130 Argentine pesos each (in August 2012). The Argentine park had a train service rather than the bus service that the Brazil park had, which added a more natural/rustic touch, though the train service was a bit slower. We walked most of the paths in the park in about 4 hours.