The apartment is in a great location - close to the Puerta del Sol. Amazingly quiet, with very comfortable beds. Loved the small touches, like the heated towel rack, and were pleased to have access to excellent wi-fi (best on our trip), a washer/dryer, and hair dryers. Overall, a very stylish place with both modern and classic touches.
Downsides: there is some construction happening, so there are a couple of spots in one bedroom where holes to the outside are covered. The seals were strong - no drafts and no noise until later in the morning when the work started up again. But this could be disconcerting for some travelers. Also, it took a bit of effort to figure out how to operate the washer/dryer, so be prepared to Google.