I stayed at Manuel's apartment for about a week. The location was great; it's right on a lively street, within walking distance to all the major sights and close to restaurants, grocery stores, and shopping.
The apartment itself was very comfortable - quiet, roomy bed, tv with Chromecast, stove and microwave so you can cook, and washer if you need to do laundry. Also, the shower water is plenty hot!
Manuel was so helpful and communicative. He provided lots of suggestions of things to do and he kept the apartment well stocked with anything you need - plates, utensils, shampoo, soap, toothpaste, etc.
I would definitely stay here again if in Madrid!