The flat itself is very nice. Very clean, two nice balconies, good area, good building, good quality furniture. Only the shower could use a new layer of silicone. There is also a radiator in the shower which rusted bad and looks a bit nasty.
I do not agree with some other reviews that the flat and its furniture look dated: I much prefer an older, real wooden floor with some scratches here and there than a new but fake plastic floor. Same for the furniture. However it is not design either. The fact that the A/C control had a sticker "DO NOT TOUCH" on it did not feel very welcoming, I think guests should be able to choose the temperature they are most comfortable with. This flat is owned by a company that has many flats across Madrid. The person responsible of the checkin (L.) was extremely unprofessional and rude. On numerous occasions he became personal with me. He also refused to communicate over the Airbnb chat and kept asking for my e-mail address. After I had already complied with my legal identification obligations and the whole stay was prepaid through Airbnb, he told me he wanted to run extra "checks" on me because he found it suspicious I would not give them my e-mail address. He then started asking photocopies of my passport. He then told me to go waiting in the street for 40 minutes (at more than 30 degrees temperature that is). Even though the flat is nice, if you appreciate a minimum level of decency and politeness from your host, I would advise against staying here.