Kristian was out of town for the check-in, but left instructions on how to get the keys. This worked well for us and made checking in very simple. The apartment was much larger than the others we had in Spain. It is located close to both Plaza Mayor and Sol station, so we couldn't have asked for a better location.
Our only concern was that the WiFi signal wasn't the strongest in some parts of the apartment, but found that just outside the bathroom gave best signal.