We had a great stay at Chiho's appartment. It is very clean, modern, very well located (about 5 mins to a train and metro station, even for children!) and only a couple of metro stations from the city center. It's perfectly suited for 4 people ( we were 2 adults and 2 children aged 7 and 4). As it is an old building, you can hear when people walk in the flat upstairs but there was no noise at all at night (and I have a very light sleep!).
Chiho was a wonderful hostess as she picked us up from the airport and had even bought some food for us so we had something for breakfast the next morning.
I will certainly stay there again if I come back to Lisbon!