We had a great stay at Santiago's place. We had good communication in the lead up to our stay, and he provided very clear directions for getting to the property. We were met by Santiago's representative, Jimena, who spoke limited English but nevertheless gave us a warm welcome and showed us everything we needed. Malasaña was a great area with lots of restaurants and nightlife, although the small street where the apartment is based is relatively quiet.
The apartment was clean, nicely appointed and well set out for a group of friends sharing, as the lounge room can be closed off if using the sofa bed; the kitchen and dining are separate. However, unlike the bedrooms, the lounge room did not have shutters and my friend had trouble sleeping in there due to the light and noise coming in, so take that into consideration if you have light sleepers in your party. The twin bedroom is quite small, so one of my friends left her suitcase just outside in the dining area.
We appreciated the lift, although small, as it meant we didn't have to carry our bags up the stairs. There was plenty of useful printed information provided, including up-to-date Lonely Planet guides for Madrid and Spain, which were really helpful.
It was handy for a few metro stations, with Plaza España/Noviciado being the closest and most convenient if you have bags, since it has a lift. We used Tribunal station a few times as it was on a more convenient line for places we were visiting, but it currently has a lot of stairs. There are plans to install an elevator at Tribunal in the next year.
All in all I would recommend this cosy apartment for a small family or group of friends.