The apartment location is perfect to walk the city. You also get easy access to public transportation and not-so-expensive Uber rides.
It is very well equipped, and for a small place, it is very well organized. We only suggested a few improvements for the shower and a couple of details in the room, but it is truly very comfortable.
For light sleepers, the street noise can be unpleasant but to us, it wasn't a problem at all.
Highly recommended for a few nights in Porto!