We stayed at Silvia and George's place for a week and it was incredible. The hosts are very responsive and kind. The apartment is spacious, clean, modern and in a fantastic location-walking distance to La Latina, Plaza Mayor (~20 minute walk), Puerta del Sol (~24 minute walk) and even Gran Via! For the times we didn't want to walk, the Puerta del Sol metro station is about two minutes away.
The amenities were all amazing (best hairdryer ever!) and totally exceeded our expectations. Would 10/10 stay here again and definitely recommend :)