We stayed for 2 months and very much enjoyed the appartment. It’s spacious, extremely quiet, well stocked, has great AC, very nice wood floors, and the lounge looks out onto a big open space which is rare in Madrid. The neighbourhood is great and there’s a great little bar on the street that serves your typical Spanish food.
It’s managed by an agency with no involvement from the owners. If you arrive at odd hours make sure you triple check with them how you get the keys. We arrived with 8 pieces of luggage and couldnt get in until several hours later. The agency however responded proactively.