This is really a gem! Not the flashy, IKEA-catalogue style with no substance, but a lovely homey studio. The location is ideal, the place is quiet and bright, the air-conditioning unit heats it perfectly, and the bed is very comfortable. Having stayed in various short-term rental apartments in Madrid, this is the one I'd definitely like to return to. Add that Isabel is extremely kind, warm, and reliable, and check in and check out worked perfectly.
All in all, a perfect Airbnb experience!