We had a great stay in Mario's appartment. We were welcomed very nicely and Mario's friend told us a lot of useful things where to go to in Porto. The room is situated right in the centre of Porto with a two minutes walk to the main square. The room has a wonderful view over all of the city. You shouldn't miss that if you are in Porto for a trip or your holidays. The room itself is very clean and equipped with everything you might need. It is surprising to see how everything fits into the small appartment but it doesn't lack anything. We enjoyed our stay very much and I can only recommend this room to everyone!
You should only note that the small window has no curtain so the sun might wake you in the morning if you are sensitive to light. Also, seagulls can be very noisy, so you might think about bringing earplugs.