We stayed in Pilar's flat for 5 nights and it was a very comfortable flat with lots of characters. The flat has a nice garden and we can sit outside in the sunshine and enjoy. Pilar's dad came and gave us the keys and provided all possible information and he is super friendly. The flat is clean and cozy. Pilar is very helpful for providing information and kindly let us stay a bit longer in the flat before going to the airport. It is near the airport, but not far away from the tram station. It is not difficult to get to the city center. But we rented a car anyway because it is easier.
I will definitely recommend this to my friends who are going to Madrid. :)