This place has super pretty interior design (loved the bathroom especially), a little backyard/terrace which is so lovely for breakfast and dinner with your friends, where you can sit outside without being seen and it is protected from the sun so it was very cool even though it had 30 degrees Celsius all week when we stayed.
The location is also great, right next to the famous Market which takes place every Tuesday and Saturday. There's also some nice cafés just up the road and short walking distance to many beautiful areas in the city like Alfama.
We stayed with 4 people in the flat, 3 sleeping in the bedrooms, on on the sofa in the living room and it was comfortable for everyone.
The only thing I have to mention that might not be great for some groups :
The walls and doors are quite thin so you might not have as much privacy within your group. It did not bother us too much though :)
I would always come back to this place, very pretty, cosy, good location.