Fátima's place is on the main strip of the historic district where there's a lot of foot traffic and plenty for tourists to eat and shop. Remarkably, the apartment is totally quiet, as it is in the back of the building.
Great location in Porto, making most sights and experiences within walking distance. Great host.
Do yourself a favor and have Carlos pick you up from the train or airport! He'll tell you everything you need to know about Porto.