We haven't met personally Guillermo but his friend Elise who was there to welcome us. Communication with both of them before and after arrival was easy. Elise gave us her tips about the city, what was very appreciable.
The apartment is as described, quiet, comfy, lighty, with 2 spacious bedrooms and has all amenities to feel like at home. The location is very central, closed to the metro and a super market opened 24 hours a day and 7/7, ans is also closed to the major touristic areas. I definitely recommend Guillermo's place for a stay in Madrid.