Had a great stay in Regina's apartment. It looks just like the photos, nice and spacious, with a comfy bed and really good facilities. The Wi-Fi was very fast and the A/C was a welcome touch. The view over the rooftops to the cathedral was lovely, and the location was really good, near to multiple attractions (eg Torre dos Clerigos on the next street), as well as a number of cafes and restaurants open throughout the day (our top pick would be Trasca). Regina was a really good host, and was very quick to respond when we had an issue checking in.
São Bento train station is a 5 minute walk away, and the apartment was easy to get to from the airport, using the metro.
The apartment is on the 3rd floor and is located on a fairly steep cobbled road.
We definitely felt we got value for money with Regina's apartment, and I honestly couldn't recommend it highly enough if you are staying in Porto.