5 stars for everything! First, the apartment. It's absolutely lovely. The location is phenomenal, walkable to three different metro stops and tons of attractions and shops. The apartment is beautifully furnished and has all of the amenities you'd hope to find in a short-term stay (AC, Wifi, dishwasher, washer, cable, etc). Considering the apartment is on a street lined with restaurants and a disco, it's surprising just how quiet it is. Again, it's marvelous and was perfect for the four of us who stayed.
Next up is Raul, he is GREAT! He's a quick communicator, enormously helpful and all-around nice. He even helped us when we were in a quick bind to print tickets for a guided tour that didn't accept e-tickets. He really goes above and beyond to accommodate.
If you're coming to Madrid, this is THE place to stay.