Nina's apartment was excellently located and had all the amenities needed for our week long trip to Madrid; it was spacious with large soundproofed windows that allowed in a lot of light; the kitchen and bathroom are modern and had all the appliances and implements needed for a comfortable extended stay (no microwave oven but that seems to be a European preference); the wifi offered decent speeds (wish the wifi password was less complicated as we kept making mistakes in inputting it into our devices 🙂 ); water pressure was good and the bed was large and comfortable
The Tierso de Molina metro station was only meters away, two supermarkets including a Carrefour (open 24-hours) were across the square, and there were several restaurants and bakeries within steps of the apartment (the Limoncello pizza place, albeit of modest outward appearance, is highly recommended, btw)
We were able to get to all the major Madrid sights by foot (or by metro); Sol and Plaza Mayor were only two blocks away and Anton Martin and La Latina were also similarly close
We requested an early check in which was not possible as earlier guests were leaving that morning; we were allowed to arrive at the apt by around 1.30pm and leave our bags there while the place was being prepared for our stay; check in and check out were smooth; the cleaning lady was at the apt and gave us the keys when we arrived, and we were instructed to leave the keys and lock the doors behind us at departure
Keep in mind that the apartment is located on the second floor (zero being the floor at street level), and this is a building that does not have an elevator, so if you have heavy bags, you might want to anticipate some difficulty hauling them up the stairs
Lastly, the entry foyer and stair case are dark, especially if you just step in from the outside, so look for light switches on the walls that are illuminated