The place is just as described: small but clean. The major attraction is its location: Botafogo. The Flamengo Metro station is about 5" away on Marques de Abrantes.
Do not be discourage by the lack of illumination in the halls; it seems to be a Carioca custom to have a single light bulb illuminating the whole hall.
I will stay at Paulo's apartment for sure next time in Rio.