Our stay was perfect at apartment.
The apartment is incredibly well located for tourists with the main museums and park very close and the trendy/nightlife spots walkable but far enough away for noise not be a problem.
The place is well located for the metro and walking distance to the main train station.
The apartment itself is very efficiently laid out with everything you need. I think it feels bigger in reality than the photos quite show.
The communication was excellent, attentive and very clear. Our flight was delayed so we could not check in during working hours but the automatic key collection was clearly explained and easy to follow.
I think this is a brilliant apartment for seeing as much as possible of madrid as easily as possible. A big 5 stars from me.