As a Superhost myself, I would highly recommend anyone planning a trip to Madrid to stay in Christian's place.
Location: A short stroll to everything the city has to offer - all attractions, restaurants, cafes, bars, metro. The apartment is a prime location but is quiet and peaceful at night in the bedroom - no street noise.
Space: Well equipped, spacious, comfortable and clean - everything you would need for a short or long stay in Madrid. My trip was in winter, and the apartment was always warm, cosy and quiet.
The Hosts: Accommodating, super-responsive, and full of knowledge about what to do, see and eat in Madrid. Will stay again, and highly recommend.