The location is great - many sightseeing points of interest in the city are within walking distance and there are lots of restaurants/ clubs/ coffee shops nearby. There is actually a club right downstairs and it is quite noisy at night, so I would recommend the place for a younger group.
The apartment is clean and comfortable, and had all the amenities we needed. The hosts were very responsive and understanding, and let us leave our bags in the apartment earlier as we arrived in Madrid before noon.