We were 7 people and stayed 3 nights at Romuald & Nathalie’s place, in the heart of the Alfama district (great location). The apartment was spacious and clean, with practical locking arrangements. Romuald & Nathalie organised pick-up for us at the airport (for an additional cost), and provided many suggestions to both restaurants, bars and sights in a practical guide. The hosts were very friendly, and we would definitely recommend their apartment to anyone wishing to stay a couple of days in Lisbon.
The only thing to point out, is that the beds could have been a bit softer.