Mario's place was exactly as described and seen on the photos. It's a small place but had everything that I needed during my stay. It might be a bit too small for two people though. Location wise is excellent - a few minutes walk from San Bento train station in Porto downtown.
Mario was helpful through messages prior my trip. I did not meet Mario in person but check-in and check-out went smoothly as his friend was waiting for me at the building. The flat was clean, supplied with towels, shower gel, and kitchen utensils. Positive experience overall.