Very good location, close to everything and in a very quiet and safe neigbourhood. A good starting point to explore Lisbon from. Rui, a friend of the hosts, met me and have some recomendations of restaurants and places to see. The appartment is very close to a great observation point from where you can get a great view of the city and also meeting many locals and get to feel the vibe of the city. There are also a local pub and supermarket very close by, and a sim card shop not far from the appartment.
The appartment itself has everything you might need in terms of kitchen appliances but is quite small (for 3 people for sure) and not very well aired (there's only one window that can be opened easily, in the bedroom). Also no window in the toilet (There are few other big windows but they are very high and therefore were unreachable to me). The house is quite old and has a damp smell, and the bedroom bed is very screechy.
Overall, quite worth a short stay mainly because of the location and hospitality of the hosts. If you're planning to spend most of the day traveling - this is a good spot.