Quaint place, great location. João is extremely helpful and communicative. He wants to make sure you have a great experience both with the apt and Porto as a whole.
The location is out of the main part of the city about a block off the river, but the center is easily accessible without having the noise and congestion. We took the bus, cab, and walked in/out of the city - all methods were easy and doable/cheap.
Would highly recommend and definitely return.