Yolanda's room is nice, clean and tidy, in a nice neighbourhood and suitable for one person and for 1-2 nights. However, not more in my opinion.
The room is advertised as a 20m^2 studio, but unfortunately in reality the area inside the walls is much smaller.
I realised this immediately upon arrival, and for curiosity bought a measuring tape. Careful measurements showed that wall lengths were 3,71 m, 4,16 m, 3,61 m and 3,69 m (this is an old building; room is not precisely a rectangle). This gives for the area inside the walls little less than 15m^2. This is not an opinion - anyone can do the same measurements.
I complained to Yolanda, and wanted to cancel my reservation (of 3 weeks). She refused, telling that she has a paper from city of Madrid saying that the studio is 20m^2. However, in Madrid it is apparently not rare that to the size of an apartment is counted more than just the pure area inside the walls; for instance the thickness of walls may be added to the size. In fact, the building is an old one, and if one adds the thickness of walls to the area inside the walls, one does get 20m^2.
I would expect Yolanda knows the real area inside the walls since the room is recently furnished, and one cannot fit bigger wardrobes in the room than the walls allow. For this reason in my opinion Yolanda's information of the room is misleading.
If you rent this room and if you care, take with you a measuring tape and measure the size yourself.