We stayed at Cosy Castle for 2 nights and really enjoyed our stay there. It was a cosy place, perfect for a couple. We never got to meet Susana, but her communication was excellent. She replied promptly to our messages (we mostly used WhatsApp) every time. She was also flexible about our check-in time.
The area around the castle is very charming and quaint, and therefore very touristic. The castle is on top of a hill which is reached via steep and narrow streets. We never actually walked up the hill, always preferring to take taxis which we found to be plentiful and very affordable in Lisbon.
One last point which Susana does touch upon in her description. The apartment is on the second floor and reached via two flights of rather steep and narrow stairs. As someone else has already mentioned in their review, this rules out anyone who has any sort of mobility problem.
Highly recommended.