The stay is OK for one/two nights, but not for a week or longer.
The good thing is - the location is very central, lots of cafes and restaurants nearby.
The flat itself is actually as in the pictures.
But the owner should have mentioned in the description, that there is no window in the flat(only a small upper part of the entrance door can be opened to get fresh air). And the entrance door itself leads directly to the street(there is no small hallway or corridor, that separates the room from the street). The door has also no good isolation. So for me it was too noisy - one could hear everything from the the street, music, talks of tourist groups, barking dogs, TV from the opposite flat.
Nevertheless, it's also an experience - living in the historical district of Lisboa.