Fantastic communication from Mariana and clear instructions to get to the apartment. The apartment itself was very comfortable and a short 15 min walk to the city centre. A number of grocers nearby as well made it easy for us to make meals at home (you may need to BYO cooking oil, seasonings).
Keep in mind this is an old building which has been refurbished. Ana and Mariana have done an amazing job insulating from outside noise (you won't hear even a squeak), but the walls inside the building between and above the apartments remain quite thin. If you are a light sleeper (as I am), the noisy (or rather - inconsiderate) neighbours may give you a tough time. This is not within the hosts' control though, or a mark against the apartment itself - Mariana was responsive when we had issues with the noise in the building.
Overall, a positive experience. This was the perfect base for us to explore Lisbon from.