We rented this apartment for a family of 4. The location was very good, 2 minutes walk from the biggest metro stop of the city, by foot it's a bit from the old town center, but not a big deal.
The apartment itself is clean and offers most of the things you need. On the downside, the bathroom downstairs is a bit too small (when seated on the toilet, one must hope nobody else opens the door). Further more, the electricity is a bit old (we needed to turn on the electric heating which caused the electricity to snap). But, and this is a big plus, when sending a message, we got nearly an immediate response. Communication was top, before and during our stay.
So overall very happy with this accommodation, the few minor things made this a 4 star review instead of a 5 star, but make no mistake, this appartment is perfectly suited for a city trip to Porto.