I can only recommend Carlos and Fatima! They were responsive, pro active and friendly. On Check-In Fatima gave us lots of information about Lisbon and even sent a list of places to go the following day.
The area is nice and close to the centre! There were some people begging/shady individuals like in any other big city. The flat is close to a square with some really nice reataurants and bars! We usually took a walk into the centre of town which took us about 20 - 25 minutes.
I can highly recommend booking with Carlos as we had a really great time and having a balcony made me really miss my old flat that had one too. :)