Esther’s place is great!
Location-wise, it is at the center of Madrid, surrounded by main tourist attractions of the city. You can literally walk to Plaza Mayor from the place in just 30 seconds.
The room itself is clean, comes with a kitchen and can fit 3 people comfortably. There is a minor issue though, the water boiler is rather small. You would run out of hot water after 2-people-shower worth of water.
The host is also quick to response.