My husband and I stayed at Martha´s apartment for 8 days in june. The apartment is really amazying! We loved it! We didnt meet Martha, but her husband Patrick received us and was very friendly and kind. Martha was also very fast replying our messages.
The location is fine (about 12 minutes to the Metro), and if you like walking you can walk to lots of the places to see in Rome (for example, about 30 minutes to the Coliseum, 1h to the Vatican).