My friends and I stayed in this apartment for a long weekend, and were very satisfied. Miguel was very quick in answering to all our requests via email, and when we arrived in Porto he took some time to show us on the map some interesting places (clubs, restaurants...). With regards to the accommodation, don't let the looks of the building deceive you: the apartment is clean, spacious, with comfortable beds and a beautiful view on the Douro river.
In sum, highly recommended!