We stayed at Joao's place for a week-end in Porto. Joao is a wonderful guest ! I didn't have the chance to meet him but our check-in and check-out were organized perfectly.
The house is very well located (in the city center), clean, with 2 bathrooms (which is convenient for a group of 6 to 8 persons) and matches the description given. Joao also offered us a bottle of wine when we arrived which is a really nice attention. I can only recommend you to stay at his beautiful appartment for your trip to porto !