This place ticks all the boxes. It is modern, comfortable, well located, and - most importantly - benefits from having an excellent host who will do everything she can to make sure your stay is a happy one.
The apartment is located on the 5th floor of a block on Calle Miguel Angel, almost directly across the road one of the entrances to Ruben Dario metro. Madrid's Metro system is excellent, so it takes no time at all to get into town, and the airport is easily accessible too.
The apartment itself is very modern, comfortable, and clean. It is located in a block that benefits from a concierge. It perhaps wasn't quite as spacious as we had anticipated, but it was big enough for our needs. The area it is located in is quite a prosperous one, and felt safe. There isn't much of interest in that area, but it serves as a very good base from which to explore the city of Madrid.
Finally, the apartment owner, Cristina, needs a special mention. Although we never met her, she was always on hand to communicate with to offer advice and try and help us in any way possible. She even managed to get us tickets for Bruce Springsteen at the Bernabeu, which was amazing!