Carmen welcomed us warmly, and allowed us to check in early as our flight arrived early and we were very tired.
Her place is fairly old but clean and comfortable, and her hospitality is amazing. She also speaks excellent English.
Location is great, being really close to Atocha station from where there is a bus to the airport every 15 minutes, as well as trains to all over Spain. Although on a busy road, the room is on the 6th floor and with the double-glazed windows closed, you hear nothing from the traffic. Even my husband who is very sensitive to noise was amazed by how quiet it was.
We stayed just one day and night before catching our plane back home, but were able to easily walk from the apartment to Retiro park, the Prado, etc.