Our host was very friendly, easy to get in touch with by email and responded quickly. Also, during our stay she went all the way to facilitate us. She was waiting for us when we arrived late at night. She arranged some welcome snacks (olives, drinks). Basics like coffee and tea were also available. She gave us some maps and guidance through the area.
In general, the location of the apartment is very good, close to all facilities (restaurants/bars/clubs/supermarket) and sights, easy walking distance to the centre of Madrid, subway nearby.
Proximity of nightlife facilities comes with a lot of noise, but shutting the windows (and using the AC) reduces it to a bare minimum, did not disturbe us while getting to sleep.
The apartment is not very spacious, but big enough. The two balconies with opening doors add a lot of character.