Luis was very accommodating and communicative. He greeted us and was flexible with check in/check out. Provided us a tour of the apartment and also gave us a few recommendations.
The apartment itself is pretty spacious, very clean, and modern. Easily fit about 4 people comfortably. The smaller room doesn't have an AC, so during the hotter months, you would need to use the AC from the living room.

The building itself is on the older side, I
assume. The apartment is at the top of the building which is nice because you're at the highest floor and the view from the apartment is amazing. The downside is that the elevator is very small (fits 1 person with luggage), we just decided to take the stairs.
The location is very convenient, close to a lot of popular areas. Walkable to Botin (oldest restaurant), Plaza Mayor, Palace of Madrid, Mercado San Miguel.
Would stay here again if we were visiting Madrid again!