Pros:
Great location. The apartment is in plaza espania. From there you can reach out by foot or metro all the important places in Madrid.
The apartment has everything you need, very well equipped.
Very quiet although is in a crowded area. The windows are isolating very well the external noise.
Perfect for families because of the space and for the fact that you can prepaire breakfast or other meals.
Very easy check in/out process.
Cons:
Very few things I didn't liked. The passage underneath the building (which helps you to reach plaza espania more easily) is not so clean and some homeless people hang out there. But you can avoid the passage and use the front entrance to the building.
The apartment is good in general but needs to get some improvements.
Only local TV stations, but it is a good opportunity to improve your spanish :p