I have lived in Olga's apartment for 7 weeks and everything was perfect. The neighborhood is really safe, the metro stop "opera" is few meters away and it is easy to get to different supermarkets. Moreover, even if the apartment is in the city center, it is very quiet.
Olga replies the email almost in real time, she is able to find the solution to any type of problem, even if she is not in Madrid, and the doorman of the building is always willing to help.
The apartment is really confortable and clean, and the kitchen is equipped with every kind of appliances.
Anytime I will be back in Madrid I will be willing to live in Olga's place.