Location, location, location!
This ground-floor apartment is located within walking distance of almost every Madrid site and attraction: Reine Sofia museum, Prado museum, Thyssen museum, Retiro Park, etc. It is also walking distance to the Atocha railway station.
There are a number of eateries all around. Two supermarkets are a short walk away.
The apartment itself is super clean with pristine white walls. The living room has a window on the narrow street outside. The bedrooms (two of them, one with a double bed and one with two single ones), the kitchen and the bathroom are all further away from the front of the apartment and thus are far from road noises.
Ample storage space in the bedrooms. The kitchen is well furnished.
Pablo, the host, is affable and friendly, eager to help. He had maps of Madrid for us and numerous suggestions as to what we could do during our stay.
I have no hesitation in recommending Pablo's apartment to others and would like to stay there on future visits to Madrid.