I rented the entire place for me and a friend. There were three bedrooms, of which we used two. The rooms were big (one was smaller, but still spacious), with double beds and some furniture. There was one (big) bathroom and we had full use of the kitchen.
The flat is at the ground floor, in the corner of a central road, very close to the Saturday flea market and 5 minutes walk from the Santa Apolónia train station.
The only issues we had was a bit of "smell of old" building up when we left the windows closed during the day (for security reasons) and roadworks in the nearby street. The double-glazed windows greatly reduced the noise though.
The place was clean.
Maria has replied promptly to my messages and has shown flexibility and availability to help.
Overall I recommend this place.
For the sake of completeness, we didn't spend much time in the flat apart from sleeping, as most of the time we were out visiting Lisbon and its surroundings.