João's flat is a perfect place to stay in while in Lisbon primarily for two reasons: 1) outstanding location, right in the middle of the city's buzzing life, with loads of bars and restaurants around, a short walk from many key points; 2) it's so charming and beautiful, which adds to the whole Lisbon experience, you can feel you're in this amazing city while in the flat; it's in an old but very well preserved typical Portugese building, the small terrace has a view on the castle and surrounding rooftops, nice to chill out there in the evening, great view from the living room windows as well.
In addition, there's everything you might need and it's perfectly clean. My best airbnb choice so far no doubt.