We stayed 2 nights at Filipa's apartment.
We liked the original, vintage decor and the location was really great to get around Porto - it's walking distance to anywhere we needed to go in the center and close to a couple of delicious bakeries where we had breakfast.
Note that if you are a light sleeper you will hear the seagulls and church bells regularly, especially in the morning, and there are no shutters or dark curtains in the bedroom. That unfortunately meant a bad first night's sleep for us. We were up at 6 am.
The second night, I purchased earplugs for the noise, and Filipa's mom kindly put up some temporary curtains. That helped.