The owner is quite reactive in answering and arrival is very flexible. About the apartment, the location is perfect right in the center of Madrid with all main centric neighborhoods at walking distance. The furniture is cute and cozy and there is a heater which is quite useful during winter time.
However, a person of more than 1m85 maximum will struggle in this flat as the ceiling is extremely low and 60% of the surface is unusable due to the low corners, as well as not being very luminous. There was a very strong continuous smell of fried oil entering from the little storage room that should've been used as a wardrobe, due to which I had to take off everything from there and made the clothes and the entire apartment smell bad, so we had to open the windows every now and then because of that.