Irene and Juan's place is very conveniently and centrally located, very close to Callao and Puerta del Sol so that a lot of sights in central Madrid are in easy walking distance; also Callao Metro station and Gran Via are very close (70m). The area is lively until late - you can walk home safely late at night - on the other hand, there is always some street noise even though located in a pedestrian zone. The place is very clean, and tastefully furnished with a comfortable bed and small but convenient bathrom and shower; also the house itself is well kept.
The hosts are easily accessible and you can communicate in English.