I've been at Simone's house for three nights with other five people.
The apartment is ideal for 4 people (two bedrooms, so that we opened a sofa-bed for two of us), but really nice and clean, and the position is enough central (less than 5 minutes walking to the metro and/or the beautiful tram 28).
Simone was a really awesome host, providing us lots of useful informations and waiting for our arrive until 22:30 for giving the apartment's keys.
I can definitely suggest a 3 nights stay here when visiting Lisbon.