Sergio was not very responsive to our messages prior to arriving in Madrid, and as a result, we still didn't have the full details for the apartment by the time we arrived outside the building. We ending up being forced to wait outside the building until Sergio eventually answered the phone and told us the room number and how to get in. The apartment still wasn't ready by the time we arrived so we waited for it to be cleaned and then were not given any instructions on checkout or practical information in the apartment unit whatsoever.
No heater in the apartment, except a small electric device (a hair dryer essentially) and it gets quite cold in the winter.
Wifi was extremely unreliable and caused issues checking into our flights, etc.
The hot water in the shower lasts at most 3 minutes. Certainly not long enough for 3 guests to shower.
The apartment can fit three very tightly. There is a mattress on the floor of the loft that can sleep two closely, and a couch for a third to sleep on. The couch does not pull out but there were some spare sheets once we dug around a bit.
The glass door to the restroom is very transparent, if you're staying with others guests whom you don't want to see everything you're doing while on the toilet, this may not be for you.