We had a great stay in the apartment - two adults and a five year old. Everything was clean and working, we had no issues at all. It was very hot (about 40C) in Lisbon during our stay, so having air condition in both bedrooms and the living room was a great plus for us. The apartment has a central location in the city, so there are inevitably some sounds from outside, but nothing that really bothered us.
Commmunication with Mario was very easy. He was also very helpful and went out of his way to return some things we forgot in the apartment when we checked out.
Highly recommended!