I had an excellent stay here a few days ago for my family of 5 from California. Alicia met me right on time downstairs from the apartment and she was very cool and nice. She was accompanied by her boyfriend who was cool too. Also she helped me by booking a taxi van for us to the airport because my Spanish is not too good.
The apartment is exactly like the pictures. Very modern and clean. There was plenty of space for the five of us with four single beds plus a couch. There was one very modern and clean bathroom. Also the two balconies that faced the Callao Square was awesome. I had a fun time in the apartment drinking wine and just people watching.
As for the area you cannot ask for better. It is a five minute walk to Peurta Del Sol and everything else you can walk to like Plaza Mayor.
I will definitely stay here again if I am in Madrid. Thanks Alicia!