The location was fantastic, only 5 mins walking from Sol which is the heart of Madrid. We walked everywhere but if you need the metro there are 2 different metro lines right outside the building and lots of buses.
The flat is small, modern, nicely decorated, clean, full of amenities and the best thing is that you can't hear any of the street noises because it overlooks an internal patio. This was very important for me as I am a light sleeper.
Nader is an excellent host and extremely helpful. If you happen to have any problems be sure that he will be there to sort them out immediately, nothing is too much for him.
There are countless shops and restaurants next to the flat and also El Corte Ingles within 2 minutes walking.
We will stay here again whenever we are back in this incredible city that never sleeps.