Margarida and Manuel were the loveliest hosts I have ever had. They came to collect us from the airport and gave us a whirlwind tour of Lisbon, with lots of helpful tips about places to visit.
The flat itself is lovely. It's really well decorated and maintained, and situated in a nice quiet street, by close to all the action. One additional perk was that it has very good blinds, so it's perfectly dark for getting a great night's sleep.
I'd thoroughly recommend staying with Margarida and Manuel. They obviously care a lot about their guests having the best possible time in Lisbon.