Nothing but good to say about the flat and the hosts !
The flat is spacious and perfectly clean, feels brand new. There's pretty much everything you could need ammenities wise, and little attentions such as coffee, fruits etc. It's cosy and comfortable.
The best point probably is its location, 3 min to Baixa with the elevator (50m from the flat), 5 min to the old Alfama. Its pretty much as central as it gets. Pastelerias, restaurants, supermarket: everything is available within 2 min walk.
Margarida went out of her ways to welcome us late at night despite our flight being 3h late, to show us the flat and neighborhood, and answer our questions. Communication was otherwise very good too.
We highly recommend the flat for a few days (or more) stay to visit lisbon.