I didn't get a chance to meet Mario but communication with him was on point.
The apartment was a good size with a nice terrace in the back. Small kitchen with the basics. Bathroom is a good size. Overall very clean. Access to the building and the accommodation is set up to make checking in and out really easy and flexible. I personally didn't have to wait for anyone to come and meet me since there is a system in place which the host gives very clear instructions about.
The place is centrally located.
Mario's app is pretty cool. It has a lot of tips for bars, restaurants, shopping, sightseeing etc. as well as a map of where to find all those places and routes suggested by Mario. It definitely made my two day stay in Porto much easier.
Thank you Mario!