I had a great stay here for 5 weeks and the place is excellent value.
The apartment is located between two quiet, picturesque, and relatively upscale small neighbourhoods: Estrella (more residential & traditional) and Principe Real (more shops & restaurants). There's several small parks nearby including the spectacular and peaceful Jardim da Estrella at the top of the street, and Praca das Flores down the street. Lots to do in the neighbourhood for visitors.
The apartment is set in the upper floor of a small house in a gated mews, itself set back off a quiet street. So you have quietness-squared, zero traffic noise and occasionally lovely birdsong from the parks and gardens nearby. The apartment itself is surprisingly roomy: more than the photos would suggest, and I found ample space to make it feel like a real home for 5 weeks. The kitchen is modern and well-equipped (albeit utensils are a little absent), the bathroom modern with endless hot water, the living room spacious. The bedroom is in the converted roof space (up some stairs) and has lots of space and a nice (if small) view across towards the garden at the back of the Amalia Rodrigues Museum - where you can hear the late-afternoon shows at the weekend.