The Brazilian side of things gives you a more distance view of the Garganta del Diablo , which is the most spectecular of all waterfalls in Iguazù area. However there is a very nice walk along the Rio Iguazù with views on all Argentinian waterfalls and there are some nice lookout points that are close to waterfalls on the Brazilian side which was in the summer heat very refreshing. However because the Brazilian park is smaller and there are less options of what people can visit it feels a lot more crowded than the Argentinian side. Maybe it was also the effect of visiting of Sunday, that Ißm not sure about. Animal wise you have the coatis that stop you from taking a lunch break on the floor, some other monkeys and the raptors flying over the falls. 

All in all the park with these waterfalls is really a must see and even more a must experience!