I stayed at Paula, Raquel & Martha's place with my husband and 2 sons ages 5 and 9. The apartment was perfect for our family! It was clean and comfortable with everything we needed to feel like home. However, the weather in Porto was unusually hot when we visited, so it did get a bit warm on the upper level of the apartment.
The hosts have a binder of information about what to see and do in Porto, and have invited guests to leave their suggestions for restaurants and activities in the city, which we found very helpful.
The location was great for exploring the city. Porto sits on a hillside, so be prepared to walk up and/or downhill no matter where you are going.