Pros:
The apartment has a nice and large living room, a big bedroom with a double bed and a small bed room (smaller than on the photos) with two single beds. Perfect for 4 people.
The apartment is functional, and has a well-equipped kitchen.
There's a big balcony with a great view over the street below - and a hammock, which the kids loved.
We had a very good communication with the agency that manages the apartment, they were very friendly and answered requests quickly.
Cons:
The apartment is noisy, lots of traffic in the street below, barking dogs, people screaming late at night, trucks collecting garbage at midnight and again at 7 in the morning. When windows are closed you hear much less of it though.
There's a foul smell in the kitchen if you don't keep the windows open.
The shower did not work very well, and water would stagnate in the bathroom sink, making it quite dirty after a few days.
There's an espresso machine, but impossible to find capsules in the supermarkets closeby, would be great if those could be provided (we finally found them at Lidl).
The apartment is in a very touristy part of the city, so 90% of the people in the streets will be tourists, however, that tends to be the case for much of Lisbon - if you want to discover real Lisbon life with real Lisbon people, go out early in the morning or late at night.