I've stayed with Roberto for a week during my vacation in Madrid. The place itself is great! The location is perfect, you can walk to the city center (Plaza Major, Sol, Retiro Park, Prado etc) or otherwise ride the metro, which is on the end of the street. The house itself is also very comfortable. We had our own room with bunk-beds, there is a guest badroom (which you only share with other guests) and a shared kitchen and living room. Roberto is a very friendly host. He lets you live freely in his house and if you have any questions, he is always very eager to help. He gives you tips for place to see/where to eat/where to go out. He recommended us to go to Toledo (a medieval village nearby Madrid) and we has such a nice time there. Also, in advance, he sends you a whole document which contains tip and tricks for places to go when you are in Madrid.

If you are looking for a nice and quiet place in Madrid, I should definitely recommend you to stay at Roberto. We had a great time!