Mariza's place is just what you are looking for if you are planning on visiting Porto. It is within walking distance to every monument and city landmark, and it takes merely 2 minutes to get to Trindade station which is the biggest metro station in Porto.
When we arived, Mariza was waiting for us and she gave us a warm welcome and she even gave us a bottle of wine as a present.
The flat is just as the pictures look and it was very clean.