Nice apartment, clean and well equipped.
Very central to city centre, shops, restaurants etc.
Host was very nice and friendly.
What I missed in the other reviews is that the apartment is on the ground floor at the street level. The windows have been blurred so people can not look into the apartment (but that means that you also can't look outside). Not a lot of traffic but you can here people talking and yelling in the street (even late at night). Also the walls are very thin, so you can hear the neighbours talking and other people in the building. I guess that is just normal in this central part of Madrid (or even in Spain), but good to know on forehand if you expect a quiet place.
Even though nice place to stay and I would recommend it if you want to stay in the centre of Madrid.