The stay at Joao's was absolutely perfect for what we wanted. Its a beautiful place with a great little roof terrace to relax on. The location is ideally situated for whatever you want; there are bars, shops and restaurants right on your doorstep (but its not too loud at night), and the rest of Lisbon is a short walk or tram ride away (and its only about half an hour on the underground from the airport).
Joao was incredibly helpful; meeting us at the flat with the keys even though our flight was late, giving us local recommendations, and just generally being a great host. I am 100% staying here again if I come back to Lisbon; could not recommend enough.