Great location to stay and use as a base to explore the city. The apartment is spacious and felt clean upon arrival. Very quiet at night, the only exception being someone in (or close to) the building having a party on the first evening until 01.30, but guess that can happen anywhere. As others wrote, a lot of stairs to reach the place but this was not a problem for us.
Furniture and bathrooms are very basic and feel rather dated. Some real misses on the apartment where a few doors which cannot be properly closed (not handy when staying with multiple families), the shower head cannot be hung normally and it was not possible to get 2 sets of keys (again not handy when staying with multiple families).
A big miss was that the promised baby bed and high chair were not there upon arrival and it took about 24 hours to get these. Communication around this was mediocre but promises twice not kept. In the end sorted OK though and we had a great time in Lisbon. Great city to visit but next time we'll book another place to stay.