The place is nice. The apartment is about 25 min walk to the Luis Bridge. The way back from Porto is all uphill, so you should be ready to walk!
The metro is about 7 min walk so if you decide to use that it's pretty quick in and out of the center of Porto.
The only problem with the apartment is that it is located on a busy street corner, and has old windows. It is very loud, even at night time, but if you don't mind city noises, then it's not a problem.
Overall good experience, would return!