We had a wonderful time staying at Mario's place during our trip to Mexico City. The apartment is very centrally located (~10 minute walk from Chapultepec park or the Roma or Condesa neighborhoods) and in an area with lots of restaurants and what seemed like a good deal of nightlife. Despite the bustling neighborhood, the apartment itself is quite peaceful and pretty quiet at night. Mario's place is very spacious and he's been very thoughtful about providing a lot of ammenities for his guests to use (e.g., toiletry products, cooking supplies, etc.). We also loved all of the decorations that Mario had -- really gave the place a lot of character. One small note, the airconditioner mentioned is a plug-in unit, not a wall-mount or central AC, however there's another fan provided for the second bedroom. We travelled there at the end of July/beginning of August and although the apartment got a bit warm during the afternoon, the weather was largely pleasant and the apartment gets a nice crossbreeze with the windows open so it was easy to cool down.
Mario is also super responsive and when we had an issue with the hot water, he had some people come over that same day to help us with it. He was also really helpful in arranging us a ride to the airport at the end of our stay. Overall, staying in Mario's place was wonderful and if we're ever back in Mexico city, we'd definitely book it again!