Our stay at Iryna's was wonderful,- we stayed for a week and the apartment was nicely decorated and equipped with everything a guest might need (even the adapter plugs). The Royal Place and the Cathedral can be reached in 13-15 minutes on foot. Other landmarks such as Puerta del Sol and Plaza Mayor are about 20-minute walk from the apartment. For everyday needs, a Carrefour Express is a stone's throw away and a larger DIA is just a 5-minute walk away.
The only downside we would like to mention is that the water pressure is low, so you have to be patient and bring plenty of time to shower ;) BUT all in all we had a wonderful base to explore Madrid!