Our experience staying at Mario's apartment was great. His friend was waiting for us to arrive and gave us a nice introduction to Porto with recommendations and a map. The apartment was very clean, nice, and exactly as advertised. The location was so convenient so we could walk to everything we wanted to do, but because it was central it was also loud at night. We also walked to it from the train station. If you are not a super light sleeper, I would definitely recommend this apartment.