Great location, plenty of room, looks just like the photos. This clean, modern flat was perfect for my friend and me--plenty of room, and we each had our own bathroom.
As others have mentioned, there are no windows. We didn't spend a lot of time in the apartment, and when we did we could prop the doors open for some air. There are fans to keep you cool at night, which worked well for us in September.
The kitchen is stocked with essentials (dishes, glasses, silverware, some cookware). The apartment is on a quiet side street, but it sits right on the street. When there are cars (or people) you will hear them. But, this is not a main road so traffic is minimal.
The apartment is literally next to the Rastro Flea Market, which is a fun Sunday activity.
Our host was good at communicating and when we had a minor issue come up, she took care of it immediately.
Location is great, you can walk all over Madrid from here. Nearest metro stations are about 10 minute walk.