William was a great host, very welcoming and very communicative. I felt very relaxed at his place. It was clean, good value and well-located.
However, I would like to note that whilst the host and the listing were faultless, there was some noise from other apartments in the building during my stay. Whilst it didn't bother me too much personally, I know this may bother some people, so I feel like I should mention it here.
Nevertheless, I had a great stay with William and would recommend it to others coming to Madrid.