I didn't meet the host, but she arranged and prepared everything for a smooth arrival. Everything (furniture, utilities) in the apartment is in a very good condition, however it should be mentioned in the listing that the central heating starts working from November 1st on. Furthermore, even if there is plenty of light in the apartment the windows do not face a street, but the internal open space of the building, so don't expect to have a view of Retiro.
The biggest advantage of this apartment is its location, right next to Retiro park and in walking distance from all places of interest in Madrid. Plenty of restaurants and bars around.
Overall I would highly recommend staying in the apartment.
The only thing that I did't like was that when I contacted the host because I had to leave several days earlier due to a family emergency and asked if I could have a discount, she never gave me an answer. A simple no would have been ok with me, but it really made a bad impression that she didn't even answer.