I had a great time at Roberta's apartment. She's very nice and attentive, told us everything we needed to know about the surroundings and even left us some pastries. The apartment itself is also good: spacious, clean and well illuminated. It's close to a lot of attractions at walking distance and all the others are quickly reachable by subway or bus. It's also close to a great gelateria - it's on Roberta's guide, check it out.
So, after all this, I obviously recommend the place. Obrigado, Roberta, até a próxima :)