A very good option in Porto, I would recommend it. The apartment is small but small but comfortable and well furnished, ideal for one person or a couple for a few days in Porto. The location is excellent, close to the historical center but very quiet. The metro (subway) station is a few blocks away and connects directly to the airport. The kitchen has everything you need for a short stay (including washing machine) and the bathroom is very small but functional. It also has air conditioning, something very valuable in the hot Portuguese summer. Communication was fluid before and during my stay. Check in and out was painless.
Only one caveat: it's three flights by stairs. People with heavy luggage and/or reduced mobility should take this into account.