I absolutely recommend Marcia’s place. It is located next to everything in Ipanema - restaurants, beach, supermarkets, metro, and also not too far away from Copa. Yet because it's on the dead-end part of street, it's very quiet.
The apartment is spacious and has all the expected amenities. There are two desks where you can work, and the Internet speed is amazing at 330+ Mbps. Nice selection of books.
Communication with Marcia was also good, and I felt that she represents genuine local host. Definitely would book again with her.