We had a lovely stay at this apartment. Hosts were super responsive and provided very clear instructions. The location is ideal to explore Lisbon: we walked pretty much everywhere, but it's close to both tram and bus lines, and about a 10 min walk to the metro. There's a bakery across the street, several restaurants nearby. The street is quiet, beds were comfortable, so we slept well. There seemed to be very few occupants in the building the days we were there.
Heating is provided by 2 electric heaters (no central heating), though it was relatively mild during our stay.
Apartment is 3rd floor with no lift, which could be an issue if you have very heavy bags (we had no problem).
Negatives: the building is quite old, so we had some issues with a blocked sink, and a door handle falling off (hosts were responsive in both cases). The bedroom with the bunk beds is pretty tight to move around. All in all we were pretty happy.