The brazilian side of the falls is, compared to the argentinian one, a lot smaller. There is one path to walk along, but you get to see the full dimension of the falls on the other side, and that is impressive! Plus you get to see the garganta del diablo from the front?. If you are a little more adventurous you could also take a 10min roundtrip helicopter flight over the falls, which seems to be pretty amazing too, but obviously does not come for free 😉 (The flight from Buenos Aires might end up being cheaper than the 10 min…)
Outside of the Entrance you’ll find a bird park, all the colourful parrots of southamerica, even some of africa or asia. It’s good to know all species that live around the area in case you see them later in the wild… and you do see at least some of them!