We stayed in Marcelo's place in Copacabana for a month and it was a good stay overall. The location is good, 5 min walk from a supermarket and 10 from the beach, but there is not a lot of restaurants/cafes/bars around - it's a nice, quiet and residential area and always felt safe. Marcelo was very available when we needed him, and the flat is comfortable, has all the amenities (including tv with lots of channels) and fast wifi.
The only downside is that because the flat is on the ground floor, the living room is a bit dark and it can get a bit noisy with people walking past your window all the time. The bathroom opens into the kitchen (no direct window outside) and needs a bit of maintenance.
Otherwise we really enjoyed our stay!