Excellently well located near the Prado museum and lots of restaurants. It is a very well equipped efficiency studio that resembles the size of a standard hotel room with a Kitchenette.
Very well equipped for everything a couple might need. When we arrived it was missing a hair dryer (for my wife) and the host quickly delivered one to us the next morning.
Excellent host, good communication and prompt responsiveness.
The washer /dryer was a bit tough to figure out, until we downloaded the user manual, but perhaps that is also due to my lack of experience with washer /dryers.
Overall a great place to stay for a couple with little luggage. An extra child is doable with the sofa bed, but note that extending the bed severely limits the moving space in the apartment.