I stayed at Ronaldo's place in Copacabana for a month and a half while working remotely and everything was great. Ronaldo is an exceptional host - he shows you around the neighbourhood when you check in, quick to respond to any messages, and quickly dealt with small maintenance issues that came up.
The location is great - a 5 minute walk to the beach in one direction, and a 5 minute walk to the metro in the other. The apartment itself feels spacious (at least for 1 person) and is well equipped for cooking, laundry, etc. Lots of wardrobe space, extra towels, sheets. Great shower pressure, super fast wifi, air conditioning, fans, big windows for ventilation, etc. The building is also on the smaller side which is nice (only 4 units per floor), and has a 24 hour concierge for safety.
One thing to keep in mind is that Copacabana is a busy neighbourhood in general, and this street is fairly noisy with car traffic. You will find this is the case in the majority of Rio however.
Overall, I really enjoyed my stay. Thank you, Ronaldo!