I assumed, maybe incorrectly, that you were referring to the Hotel Cataratas in Puerto Iguazu, but there is a Hotel das Cataratas in the park on the Brazilian side which has spectacular views. We did not have a visa for Brazil, so staying there was not an option for us.
I thought it looked really cool when we were touring the park. There is good info on both "Catataras" hotels on TripAdvisor. The opinions on both are quite varied, but I think you would probably find them helpful. The Hotel Cataratas in Puerto Iguazu is probably a ten-minute drive from the park, IIRC.