My stay at Felipe's apartment was short (2 nights) but very pleasant nonetheless. the apartment is perfect for solo travelers or couples and is fully equipped with everything you could possibly need.
In terms of location, it couldn't be better as it's in my beloved former neighborhood of Lavapiés (I lived in Madrid for 9 years!) and within easy access of other interesting areas like La Latina. The main museums are also within walking distance, as are a host of cool bars and great ethnic restaurants in Lavapiés.
Felipe was very attentive during my stay and was in regular contact with me to make sure everything was going smoothly.
All in all I would definitely recommend his apartment as a great base from which to explore the city, whilst at the same time giving a very interesting insight into one of the most bohemian, working-class and multi-cultural neighborhoods in Madrid!