I stayed at Sónia's for 11 nights for my 3rd scouting trip to Porto to explore the Foz neighborhood. Sonia's place is in Foz Velha, which is the historic area just a few blocks from where the river meets the ocean. It's narrow streets and mostly low-rise homes give the area a unique feel away from the more touristy parts of Foz. That being said, you can walk to multiple cafes, restaurants and small grocery stores in a few minutes. There is a small booklet of information but go online to get more current ideas. The 500 bus - which is a double-decker bus route along the river and ocean - stops nearby and is very convenient for getting into Porto Centro in about 15 minutes. Plus the views are amazing!
Sonia's place is spotlessly clean and nicely decorated and feels like a home, which was great for my longer stay. Like many older homes in Porto, there is no central heat (only space heaters) and it can feel chilly even when it's warm outside. So pack something warm if you're going to be spending time inside.