Well my experience was not bad. When you first arrive to the building you are greeted outside and Mary guides you in the apartment complex. At the apartment door her dog (which is not a chihuahua as other comments say) and her cat greet you. Marys hospitality is unbelievable, she quickly told us every instruction, recomendations and how to settle in. After putting our things in the room she even made her washing mashine available for us. Every morning she made us ginger tea for our coughs and there was breakfast available in the kitchen. I booked the room with the private bath which was not specified in the listing (there are other rooms), the room was big and comfortable, bathroom was spacious with a double sink.
A few mishaps of our stay were that we had to take a 30 minute train ride to the center of Madrid (Plaza del Sol), the listing states is near the center and is not. The apartment does not have heating service and it gets really cold in winter times which made sleeping a bit difficult.
When booking I recommend you clearly state which room you want because I am not sure if its the same room every time, the descriptions of the listing are not very clear.