Felipe was very responsive to our emails and flexible. He let us drop off our luggage early so we wouldn't have to carry it around with us. He was also understanding about the fact that there would be a third person staying with us for just part of the week; he only applied the extra person charge for those nights. His apartment is small, but in our experience that is normal for Madrid. It is clean and stocked with everything necessary--extra sheets, towels, cooking utensils, etc. The internet connection is good, which we appreciated very much. The best thing is the apartment's location--it is easy to get to the airport by Metro (which we did on the way in) or by Cercanias at Atocha (which we did on the way out). We didn't find it necessary to use the Metro while we were staying at Felipe's apartment--we like to walk and all the places we wanted or needed to go to (museums, Retiro, other major sights, buses leaving from Principe Pio) were within a 30-minute walk. But it is very close to three Metro stations if you prefer not to walk. The apartment opens onto a courtyard shared with the rest of the building. During the day you can hear other people talking or watching TV if you have the window open, but for the most part the neighbors are quiet at night and we had no trouble sleeping. In any case, the windows could be closed and the AC turned on to drown out any outside noise. The shower is small. We are thin but very tall and found it a bit cramped. I mention this not because it was a problem for us but because some larger people might find it hard to use the shower. All things considered, we can confidently recommend Felipe's apartment--he's a good host and his apartment worked very well for us.
If you stay here we highly recommend eating dinner at the nearby Gau&Cafe--it's on a rooftop just a few blocks away. Beautiful views and good food.