We enjoyed our short stay in Madrid. Analia's apartment was very clean, had a comfortable bed and a well equipped holiday kitchen. The location of the apartment is great - about 5 minutes walk to the nearest metro station, ~100m from a supermarket and close to a range of other shops. City centre locations are walkable but quicker to take the metro. Analia sent very clear instructions and was available when we needed further information.
The apartment seems to be in a fairly sleepy street and in general is as quiet as you can expect from a location in the city. That being said it is also a basement below the entrance to a block of 12 flats and so footsteps are fairly frequent when people leave for work in the morning. This didn't really bother us but may be a consideration for light sleepers.
Overall a good base for a few days exploring the city.