Felipe & Pilar were organized, friendly and responsive hosts. I very much recommend they're apartment. The place was great: comfortable, clean, bigger than it looks with everything you need for your stay. Being about a block from Sol metro station and with convenience stores, restaurants and more on the street, you'll have everything Madrid has to offer at your fingertips.
One tip: If you're staying in the winter crank up the heat as the placement of the radiator in the master bedroom (before the large windows) means that room can require a bit of extra heat to get warm. To be clear, there were NO problems with the heat, just be aware you will want to turn it up a bit higher than normal to keep the master toasty.