Great value. Fantastic location. A quick walk to Plaza Mayor, a few more minutes to Puerta del Sol. The Palace is also a 10-minute easy walk.
Apartment is very clean with minimal wear and tear. We didn't use the kitchen except to fill water bottles. The water tastes good.
There is plenty of hot water, but be careful using it, especially if you have children with you, as it comes out VERY hot.
The street is noisy, but the main bedroom upstairs is very quiet with the door closed. You may hear neighbors walking, talking (there was a child nearby who did not want to go to bed), or using the plumbing (which squeaks sometimes and might bother very light sleepers).
Common area lights are on motion sensors. It might be dark when you open a door. Also, there's a button on the wall next to the outside door to release the lock. Stairs are just as fast as the tiny elevator, but the treads are old wood and uneven; be careful.
Marta was in constant communication and answered questions quickly.