Everything was perfect at Sèrgio's apartment. We was welcomed by Sèrgio himself, he was very friendly and informative. The apartment is exactly how it looks like in the pictures and its location is just perfect: you can easily go to Lisbon's city center on foot and Martim Moniz metro station is just 5 minutes of walking away. I'd definitely recommend it. On a side note, if you go to Lisbon you can't miss Sintra, Cabo da Roca and Belém!