The communication with the landlord before the check-in was perfect: he did always respond pretty fast and was keen to help.
The apartment is really tidy and clean, and the location is on spot (historical city centre). It is a place to book if you intend to stay in the city centre and walk to every Oporto's attraction.
All the surrounding apartments of the city centre are small, and this is no exception. Note also that the street is quite busy, and the weekend's night is undoubtedly noisy.
In any case, I consider staying here again on my next visit to Oporto.