We spent five days at two families in Miguel's appartement. Location is great, and the capacity of the appartement (16 beds!) is great too. The place was reasonably clean. Furniture is very basic, and some of the appartment's facilities are wearing off (windows and radiators). Miguel is a great host, polite, reactive and very welcoming.
I see the appartement as ideal for a large group of people who need a central place in Madrid to sleep.