Firstly let me say that Sergio is indeed a super host and you will have a good time when staying in Rio. He is great for advice and has extensive local knowledge about Copacabana.
The penthouse is on the rooftop of the building and as such it's at least 5 degrees hotter up there than what is forecast, so although expensive to run, it's unbearable to be up there without the air conditioning. Only problem we had was this was that we were made to feel guilty for using the air con.
More than enough space for a couple. I was travelling with a mate and Sergio provided an extra mattress for the floor and that was great of him.
Also has a great outdoor shower and good Wi-Fi in the living area upstairs, not the bedroom though as they are separate.
Great host and great place to stay.