There is so much to love about this apartment, the location, the clean, efficient, well equipped space, the fact that it is located on a pedestrian only area, so no traffic noise and the quietness of the bedroom! It is also close to several Metro stops, which we didn't use, as we walked everywhere. As people have noted previously, it is located above the churro/chocolatier shop which is open 24 hours a day, so there is frequently laughter and conversations late at night, which may only affect you if you are the one sleeping on the sleeper sofa (ear plugs easily solve this issue). There is a fabulous deli very close to the apartment (in the pedestrian mall area) where we bought cheese, crackers and a bottle of chilled white wine for about €11! The apartment was also very close to Plaza Mayor and the Mercado de San Miguel which had exceptional food/tapas.
Juan was awesome to work with and exceptionally responsive, even with multiple questions during our stay. He also arranged for a chauffeur service to meet us at the airport (€30), which with the airport fees on taxis was probably cheaper and definitely more personalized and relaxing! If we return to Madrid, we will definitely be looking to see if this or one of Juan's other apartment is available.