The positive first, perfect location in Madrid if the center of the city is what you need. So location check.
The negative, the building where the apartment is located has a terrible smell of cats, specially as you access the stairs, by the way there're a few steps before being able to access the elevator. If you're particularly sensitive towards the smell of cat's pee I suggest you stay away from this property. Fortunately once inside the apartment the smell is not percibable. The apartment is nicely decorated although it needs some care, pieces of trim are missing, a kitchen cabinet door is hanging lose, the shower needs new silicone grouting urgently...just to mention a few details than can easily be fixed. To access the building you must go through a bar, the bar wasn't open to the public when I was there. Don't expect a conventional building door. I think a picture of the front of the building would actually help future visitors decide on this apartment.