We went to Madrid on a family trip (7 of us) and were excited to stay at this apartment because of its location and because it has 4 bedrooms.
The location did not disappoint, it is just a few steps from the Puerta del Sol and all of the area's entertainment, cafes, restaurants and bars. Many of Madrid's most important sights are within walking distance (Plaza Mayor, Royal Palace and Opera, Prado Museum, to name a few).
The building's facade is a bit rough, but inside it's nice enough and has a small elevator. The apartment is located on the first floor.
We were taken aback by the tobacco smell when we walked in but it faded away after leaving the windows open for a few hours. The A/C worked well, which is no small detail in an European capital city in the summer.
We were also unhappy with the size of the beds, as we had asked and were told they were 1,8m x 2,0m (which is king size), but they were closer to queen/doubles. It's important to be truthful during the reservation process, so that we can make informed decisions on where to stay.
My wife and I didn't enjoy our first night as much as we hoped, because the pillows, sheets and comforters smelled awful. We contacted Irina, our host, who was very apologetic and helpful and had all of the master bedroom's linens and pillows washed. However, she should have washed all of the apartment's linens, since they all smelled. We didn't press the point because she let us know how difficult it had been to wash the master bedroom's. We also suggested they invest in newer sheets, pillows and towels as they are of cheap quality and are very much used.
Otherwise, we really enjoyed our Madrid stay, but will be more careful next time we book, as we expected more from this apartment.