Can't say enough wonderful things about this place and about Miguel. For starters, Miguel got in touch with us a few days before we were scheduled to arrive, gave recommendations and made sure we were well set up. He even went so far as to help us get tickets for the soccer match that was happening the night we arrived. When we arrived he had set out a bottle of wine for us.
The apartment was small (by suburban American standards) but still very spacious and we never felt cramped. The shower is pretty small and at a minimum there is a flight of stairs to go up after you get off the small elevator. Often we took the stairs all the way up from the door to the apartment in a futile effort to combat the fantastic food to be had in Madrid. The apartment is perfectly located right on Plaza Mayor. During the time we were there the Festival of San Isidro was going on and there were concerts every night. We could go out on the plaza and hang with the crowd or we could sit on the balcony with some wine and listen to the music. Once the concerts ended and the crowd dispersed there was not much street noise at all.
Almost everything is within walking distance. We walked to the soccer stadium, to all of the museums, to restaurants and to shops. The only taxi we took was to the apartment from the airport and from the apartment to the train station when we left Madrid. Though in fairness you could walk to the train station, we just didn't want to with our luggage.
In short, great host, great apartment and great location.