This is a great place to stay.
Room is comfy and spacious. The apartment is quite nice and it has an amazing location. It is just across a metro station, in a neighborhood full of shops, restaurants, cafes and bars. It is also walking distance of a lot of attractions in Madrid.
Juan Carlos is an amazing host. He had a lot of little but nice details: from giving us a city map with "touristic circuits" made by himself to providing water, bread and juice and borrowing an umbrella.
There is another airbnb room in the apartment. So you might be sharing spaces(restroom and kitchen) with other guests. In our case we actually didn't get to see them.