We really enjoyed our stay in Madrid and the apartment for the full 5 days. First of all, the apartment was clean, tidy and had everything we needed. Thereby, the location is just perfect. It's located in the centre of Malasana (Plaza de San Ildefonso), a really vibrating and fun area and close to the metro (Tribunal) as well. Lots of nice bars, coffee shops, shops, restaurants, etc. in the neighborhood. And all (i.e. the city) is easily accessible by foot (we only took the metro from and to the airport).
We also immediately felt welcome in the apartment (Enrique personally handed over the keys when we arrived) and the apartment gave us positive vibes throughout our whole stay. We can only recommend this place, and to be honest, we would love to stay here again when we return to Madrid. And this last thing will definitely happen, since it's a great city to discover and enjoy!