As the Dermatologist about moles and Realtors say: Location, Location, Location. The best of this cozy apartment is its location. There are nice little cafes and basic grocery store downstairs, money exchange around the corner, train Station (where you can go to Toledo o Barcelona for a little money) 1 block away, 10 min walk from Del Prado Museum, half a block from Reina Sofía Museum.
Enrique is the King of the tips around, fast responder.
The only drawback is the 4 stories w/o elevator. Saying that the check in and the check out can be a little bit challenging if you are carrying a lot of baggage. Not a bit deal if planning to burn the extra calories from Tapas and churros.