I stayed at Alberto's lovely flat for 10 days; it is a very brightly painted and nicely decorated flat, with lots of useful equipement (cooking plates - I would love to have the same at home- microwave, all materials for ironing and washing clothes..). Though it is located in the center of Madrid in a lively area, we slept very well and the building is quiet. The flat is at the first floor and Alberto's shop is downstairs, making it easy to reach him in case you would need it.
Alberto is a very attentive host and took care of us, answering all our questions and providing us with informations when we needed. Definitely a great host!
The location is fantastic: close to the lively Cava Baja where all the locals go for tapas and drinks, and close to vibrant Sol and Santa Ana, making it easy to reach any destination such as Tribunal and El Retiro. It never takes more than 30 minutes to go somewhere far, and most of the touristic attractions are reachable by walk.
So I would definitely recommand anyone to stay at Alberto's flat to enjoy a great experince of Madrid!