The room and apartment were very clean and the location is just perfect. Within walking distance are museums (such as the Prado, the Reina Sofia, among many others); the large Retiro park; the old city center (Plaza Mayor); and many pubs and restaurants. Yet the street itself was very quiet during the night.
Elvira gave me a warm welcome and took the time to provide information about the city and locate interesting locations on a map.
So I'd definitely recommend this place.