First, the check in was very easy. The communication with the host was very easy and he was very helpful. You have to pick up the keys from their office which is located 7 min away from the apartment.
The apartment is very spacious and very well located in the heart of Madrid just near la Plaza Mayor et la puerta del Sol. It exactly looks like the given photos. Most importantly, it is clean and provided with essential amenities (shompoos, towels, coffe and tea, fans, ...).
Howether there are a few thinks to know. It is not very well isolated. Some of the heaters don't work and it gets cold during the night. Plus you can hear the neighbors going up and down the stairs and also a sort of hair drier noise all night long. The wooden floor makes a lot of noise when you walk on it.
Overall it was a great experience and we hope to come back to Madrid soon.
Tip: There is a locker service at the office where you can pay and reserve online the locker to leave your suitcases.