Very nice and quiet room, just as Luis says. The room is located in a lovely neighborhood that has a vibrant night life yet doesn't keep you up with noise at night. A nearby street is lined with bars with great food and friendly locals, and an even larger food and shopping district is just a street over. The room is also next to a park and a green courtyard that the birds like to visit, even though it's December. It is also a short walk from the metro, bus stations, and Berlin Park, which has remnants of the Berlin Wall.
Luis was very helpful, friendly, and understanding. He was happy to meet me for check-in even when I was unable to meet at the agreed time. He pointed me to all the local sights and gave me advice on navigating Madrid. The room he prepared for me was clean and I was allowed to use all the promised amenities. I would highly recommend staying with Luis if you plan on visiting Madrid. It's hard to find such a great host with such a low price.