We arrived early by train and were able to put our suitcases into Enrique's office. Enrique was very responsive throughout the whole process. It was only a short walk from the office to the apartment so we were able to walk there easily. The apartment is centrally located in a little side street. While it may not look safe for some people at the first glance I think it's a fairly safe place. There are many people walking by and the Indian restaurant in the first floor has very good reviews (and is very good).
The apartment was very clean with everything we needed. But I called it functional. 4 out of the 6 bedrooms have no windows and are somewhat tight. And the bathrooms could use some more paint (or paint removal on the floor). We staid in 4 other apartments in Andalusia for about the same price but with much higher quality. So our bar was probably set to high for Madrid. Initially we were a bit disappointed but after two days it worked out very well. We could walk everywhere, it was quite at night, everything was clean, and we had everything we needed in the apartment.