The location is perfect if one wants to explore but enjoy a quiet night! The Santos train station is just a few min walking down the main street. The little store by the next cross street sells train/bus/ferry tickets (also day tickets) to avoid standing in line by the few ticket machines. Easy walking and travel to all highlights of Lisbon (old parts of town, Belém, ferry to Almeda for an amazing view of Lisbon, easy travel to Sintra, Cascais, etc) - taxi/busses/trains nearby. Bring comfy shoes and be prepared for some ups and downs.
Marta‘s place has a large 3rd and 4th floor (no elevator!). Perfect for families with kids 6+ or a group of friends - the bedrooms are very quiet - we didn’t have to use the AC, and had windows open - everyone slept well in the comfy beds. The washing machine was a great plus as we try to travel light. The flat was nicely decorated and all was clean and comfy. One of the best Airbnbs’ I’ve stayed in so far (and they’ve been many!).