Iguazu is very close at the border between Argentina and Brasilia; so due to that reason you can (and should) visit the amazing Iguazu Falls from both sides Argentina and Brasilia.
In this blog post you get the impression from the Argentina side.
From the Argentina side you can walk very deep into the Iguazu Falls and really feel the power of the water. From the Brasilia side, you have a greater view but more from the distance – there is only one path to walk between the masses of water in Brasilia.