This is a great place.
The apartment is in a very busy area, and it can be noisy in the apartment, but it was never much of a bother. Everything in Madrid's city center is walkable from the apartment and the metro is convenient if you prefer not to walk.
The apartment was very clean and comfortable. The apartment was bigger than expected and plenty of space for our family. Check in was easy and communication with the host was quick and efficient.
The apartment is identified as ground floor, but it is actually up one small flight of stairs above some street level shops.
I would be happy to stay here again.