Sergio was extremely responsive, check-in was easy, and building was centrally located to everything and felt safe. City Center and most tourist spots are walking distance, there are many bars/restaurants/shopping in the blocks surrounding the square that the apt looks over.
The only thing - the apartment's heating/cooling unit is not working. It is December and at night, Madrid can get fairly cold and so can the inside of the unit. While I knew the apt didn't have A/C - it also doesn't have heat, so at night it can get pretty cold and I had to bundle up at some points, especially if you use the patio and air sweeps in from outside. It wasn't much of an issue during my stay but if it were colder outside I may have been.
Great stay, would book Sergio's place again for the location, view, easy access, and cleanliness. The view from the balcony overlooking the square was GREAT to wake up to.