Nice apartment newly refurbished with nice furniture. Very central location, you can literally just walk everywhere.
Marcelo was really friendly and helpful, he also suggested us few good restaurants.
The only not so good thing about the apartment is that there is only one window and not much day light coming through. However we stayed in the apartment only to sleep and also because of this the place quite cool in the hot Madrid summer so this didn't bother us much.
Will definitely consider this place again on my next visit in Madrid!