Easily the best thing about this apartment is the Atocha/Barrio de las Letras neighborhood. The building's front door is on the busy Calle de Atocha and is walkable to everywhere - train station, museums, parks and plazas. Pedestrian lanes next to and behind the building are full of little markets, restaurants and open air plazas. All we had to do to eat well is stroll a little ways down these meandering streets. We had everything we needed in the super clean apartment. The check in process was seamless and response to our WhatsApp messages was very quick. The apartment felt a little sterile and impersonal since no one ever lives there even part time, but that wasn't an issue for us.
As other reviewers have mentioned, the bed is saggy. My husband had to sleep on the couch after the first night. Before our arrival I asked whether the bed had been replaced after Madflats replied to these customer complaints that they would fix the problem. The reply was "the bed is in perfect condition, both in the room and on the sofa." It's probably fine for one person, but for couples it sags.