Before we visited the host provided a helpful and comprehensive list of things to do see and enjoy. She also contacted me direct to offer help/suggestions via WhatsApp.
The Flat is close to the centre and the main tourist attactions. It's on the 28 tram line and has a selection of shops/bars very close by. (On our trip we discovered Lisbon is very hilly and this is at the top of one of the highest peaks so you may want to take a tram/taxi with your luggage).
The owner met us at the Flat and was extremely polite and helpful with the area and with suggestions and a bottle of wine! It is a traditional style property with a great balcony (sunny from mid morning until late at night ideal for relaxing with some wine) and all the other facilities you'll need for a short break.
Lisbon is a lovely city ideally set up for tourists and walkable (with a few steep/ very steep hills). I'd recommend getting a travel card and visit Belam (2 miles along the coast and also take the ferry across to Cacilhas and Almada).