I booked Fernando's apartment as I was in Madrid on business. It was one of the best Airbnb's I have ever stayed in. Stylish, clean, comfortable and full of details that make you feel welcome (he even put a bottle of wine in the fridge!).
The area was also spot on. Centrally located with lots of good cafes and restaurants around.
Fernando, the owner, was helpful right from the start, making sure I was enjoying my stay and letting me check in a little earlier than planned.
If you're coming to Madrid then you really can't do much better than this!