Apartment seems to be managed by someone other than the owner but they were excellent with great communication before and during stay - quick to reply and very helpful. We picked key up from local collection point which worked well on the way from the station. We were allowed to leave the keys in apartment at end of stay which was also very convenient.
Note there are push buttons near the gates to the complex to let yourself out - they are fairly obvious but we missed them initially! Apartment is secure, in fairly good condition (couple of cracked floor tiles were noticeable) with effective shutters and air-conditioning to keep it cool . It also had good kitchen facilities - We missed not having a dishwasher but appreciated the washing machine. Neighbourhood has some great bars and a supermarket (Lidl) very close and we felt safe. It was relatively quiet for a city location (you naturally hear bin lorries, buses go by etc) but certainly we experienced very little noise from other apartments which was great. The bed was also extremely comfortable (and did not resemble the day bed in the photos which was a bonus). The location is within 10 mins easy walk from the Atocha station and so was perfect and there are various Metro stops nearby to get around the city if needed. The only thing we would have liked was a bit more detail of the rubbish bins in the street, as there seem to be large bins to use and smaller wheelie bins too and we were never quite sure if we were allowed to use the bins we used! :-) Also one thing to note - don't use the "light switches" immediately by the flat door as it is actually a door bell - the actual light switch is on the right as you come into the final lobby that leads to the four flats. As flat is on first floor we didn't use the lift except with our luggage when we left.