Gonçalo is a great host, very kind and smiley, responds really quickly and with extensive and accurate information. He met us on arrival and explained everything about the flat, gave us a map of Lisbon and pointed out the main areas and sites of interest. He also left us a very useful list of great local restaurants.
The flat is lovely and clean with a modern vibe and has everything you need for a comfortable stay. We loved it that it was in an internal courtyard of a real residential block. It felt safe and gave us a sense of what it is like to live in the centre of this wonderful city. It is very close to the main avenue and the Rossio train station (10 minutes walk; trains to Sintra run from there) and yet it was really peaceful and very quiet at night. The view from the walkway terrace is amazing and it is a sun trap so if you feel like tanning for a couple of hours or having your breakfast al fresco you could do it easily (even in March, the weather was great). Another benefit in a place like Lisbon, where you are constantly climbing steep hills, is that you can get to Gonçalo's place over flat terrain from Rato tube station (10-15mins walk) - definitely helps if you have luggage!
Overall, highly recommended and a great place to stay.