We stayed at Ricardo's in November 2012. He and his brothers are very welcome hosts. They were always ready to help, provided us with all necessary information about Lisbon (where to eat, what to watch, where to do shopping). They were very friendly and polite. As for the flat it really has a great view, it is very clear and comfortable and situated close to the city center and to Sao Gorge castle.
We enjoyed being in Lisbon a lot and hope will come again and in this case would gladly stay at Ricardo's again.