My wife and I stayed for over a month at Regina and Vital's place and loved every minute of it. The location is perfect. You are a 5-10 minute walk from the Porto Cathedral, the bridge, the riverfront, etc. The Sao Bento metro is conveniently 5 minute walk away. Torre De Los Clerigos is directly outside the apartment, making it quite easy to find your way home by just looking for the tower. A very safe area! You are surrounded by amazing cafes, restaurants, bars, museums (two right outside), etc. Only downsides: Small shower and there can be some noise late at night on the weekends from people leaving clubs, but not too terrible.
Regina and Vital were amazing hosts. They made check in easy, communicated with us very quickly, and would confirm every week when we would like the housekeepers to come (housekeeping is included and once a week). We even locked ourselves out one day and Vital quickly came over to help us get back inside. Overall, I would highly recommend this location!!!