We stayed here for two weeks, and used it as a base to explore Madrid and surrounding towns.
As others have said about this place, it has a great location, very near the major museums, close to many restaurants and tapas bars, and walkable to many historic sites. Atocha station is just a 20 minutes walk away, several metro stations are within 10 minutes.
The apartment is in a busy area, but it is very quiet inside. This is in part because the apartment is on the inside part of the building , looking out on a courtyard on a low floor. As such, it is a bit dark and lacks a view. But it is very, very quiet at night, which is probably unusual here. With the shutters closed, it is very dark and quiet, and we slept better than anywhere else! There is some inside the building noise, from neighbors and from the restaurant downstairs, but by 12 it is quiet.
We didn't cook, but the kitchen looks fine. The washer/dryer is very convenient. Plumbing and Wifi are also great.