Me and two friends of mine had a nice stay at Sabrina's place. She was very friendly, flexible and gave us some tips for Madrid. So the communication between us went excellent.
The flat is located perfectly for most of the things that you want to see during a short visit in Madrid and well equipped for basic needs. Also there is a little patio/corridor front of the appartement which is very cozy in the mornings. For 3 people it's a bit crowded but still managable. The only downside of the appartement was that the ventillation of the bathroom was not very good which caused a bit of musty air in the appartement. But for a short stay it was still okay.