STAY: 4 nights. One of my favorite things about Airbnb is the opportunity to stay in older, traditional homes to get an appreciation of typical housing setups worldwide. The Santa Catarina home is one of those. You get a rectangular, 3rd floor, walk up apartment with dining/living facing the street and bedroom/kitchen in the back. The bedroom and kitchen are separated by a SMALL bathroom.
The location I found to be quite handy to see the major points of Lisbon. You are in the Baxia-Chiado area but the place itself is removed a block (at least) from where all the people are carrying on. There are also devices to block general traffic from entering this area so there are almost no vehicles passing directly in front of the building. We experienced no noise problems overnight either from outside or from within the building, which is remarkable. (Thick masonry walls are good for that.)
The bed we found to be a bit too firm. Shower (after a minor condition issue was corrected by Carolina) was adequate with an on-demand gas powered water heater handily doing its job. Note that heat is provided by two portable electric heaters, which do the job but can take awhile to achieve a comfortable level.
Having now had this experience I would, for the next Lisbon visit, opt for a place that is less rustic and with a larger bathroom, but I would say this place is a good option for most first-time Lisbon visitors.