This was the second time we stayed at Sónia's place in the old part of Foz, and our experience was as excellent as at our first stay.
The apartment has a spacious kitchen with a large table and everything you might need, from dishwasher over microwave/oven to washing machine; a living room with sofas and chairs, two sleeping rooms, one tiny with a double and a larger one with two single beds, a nice bathroom and a little backyard terrace. Everything was squeaky clean, and Sónia had even provided some refreshments for us because we arrived very late.
In just a few steps, you get to the scenic coastline of the Douro, it's ten minutes on foot to the Atlantic coast and lots of nice restaurants (check out the pizza at Casa da Foz, reserve a table!), and bus or vintage tram take you to the center of Porto in 20...30 minutes.
Sónia's parents actually live next door, being very welcoming, and she's very responsive and helpful. She also can organize a fast and worthwhile transport from the airport or station to the apartment.
The location is very quiet, you just hear the seagulls, it's away form large roads or city noises, more like being in a village. For us, it was relaxing to get back to this quaint part of town in the evening.
We'll definitely check out if Sónia's place is available when we're going to Porto again.