Stayed here for a weekend trip and it was great. We were met at the door and shown in, you have to walk through a hallway and small courtyard between buildings to get to the right staircase. The place was super clean, and the water/ac/etc. all worked fine.
The only thing that was a little inconvenient was the parking. Since we drove and were not Madrid residents, we were legally not allowed to park on the streets. We had to used a website the host provided to book a spot in a public garage. The other option would have been to park out of the city and cab/bus back in.
Overall, definitely recommend for any group that can use this size place.