We had a great stay in the appartment. Good points are that it's really big, REALLY clean, and located very well. You can walk easily towards all the nice things Porto has to offer, and subway Bolhão is close.
Things that could have been better are that it's right next to a terrace which is really busy (at least during summer). When you're in the living room, the music is really loud. BUT you can close the windows and door, so you won't hear it in the bedroom. Other thing is that de bedroom is central in the apartment building, so when somebody slams the frontdoor at night, it's really loud. Also, when somebody turns on the light on the apartment stairs, the light is entering the bedroom through a sort of window, which woke us up several times.
Apart from this, we had a great stay!!