Martha was out when I arrived, but she prepared everything with anticipation so I could get access to the apartment without any problem. The communication was never a problem during my trip and she was always willing to help me to get to her place.
She left soap, shampoo, a towel, water and a few books in the guest room.
Martha's apartment is VERY close to the subway station (3 mins walking), and this is very suitable for people who will be traveling using public transport.
Most of the time I left early in the morning and came back late in the night and never had any problem to get access to the department.
The balance cost / benefit is a very good deal.