The apartment was suitable for our family of 2 adults and 1 child. Bedroom is quite large, while the living room, when the couch is extended, can only be used for sleeping, as there will be not much space left. For us this was not a problem, since we only stayed in the apartment at night time.
The place was clean and the neighbourhood was quiet, even if very close to the centre.
One mention: the street where the apartment is located is very steep, and both street and sidewalks have cobble stone pavement, so it could get a bit tricky to pull your luggage up or down the street. But this was only a minor inconvenient in the end, since taxi fares are quite decent and this kind of street is a trademark of Lisbon. In plus, this is compensated by the easy access from there to any tourist attractions you might be intent to visit while in Lisbon.