I'd highly recommend Carlos' apartment to anyone traveling to Rio. The place is a block from Ipanema Beach, a block and a half from the metro, and walkable to dozens of bars, restaurants and amenities. The space itself is clean, comfortable, and welcoming. The apartment has both European-style and some dual European/American-style outlets. You may wish to bring a converter if you have one but it is not entirely necessary.
Carlos is a pleasure to work with. I don't speak much Portuguese so Carlos was kind enough to use English for our communications. He wasn't there for my check-in but he made arrangements for me to get the key from the doorman and things went very smoothly. I would definitely stay here again!