Mercedes was an extremely friendly and helpful host, and the apartment is perfect for exploring Madrid. Once she had an idea of what we were looking for (I wanted to visit from Ernest Hemingway shrines) she was always ready with some tips or advice.
The apartment's central location is great, as even when we were lulled into oversleeping thanks to the ridiculously comfortable bed, we could walk just about anywhere (Museo del Prado for example) within about 15 minutes. The fact that the place is just across the street from Parque del Buen Retiro meant we could also avoid some of Madrid's busy streets when going site seeing.
I will definitely try to stay here again on my next trip to Madrid.

Thanks,
Pat and Laura.