I had really great time during my stay in house of Carlos. The first and the most important thing is, he's a very good host, very friendly and helpful. He met me when I arrived, explained everything and showed the room. The room is very-very clean and so lightful and stylish. The bathroom is clean and nice too. You can also use a fully equipped kitchen if you want to. The location is super cool, you can get everywhere in no time on foot. The apartment is located on the street which is parallel to Rua Santa Catarina, it's really close to Trindade and Bolhāo stations. There are many pastelarias and shops nearby.
I hardly recommend you this amazing place if you want to have a great stay in Porto.