The apartment is exactly as described in the listing - it's a top floor open plan living room / kitchen / bedroom with a good bathroom. Hence there are lots of narrow stairs as are common in Portugal.
Location - excellent, easily accessible to the city sights, and very close to Rossio Central station to get to Sintra on the train.
Facilities - facilities in the apartment were well thought out, with a 2 pin plug for electrics, hairdryer and very good air conditioning.
The main downsides as other reviewers have mentioned is the noise - as this is a very central location, on a busy road on/near Bairro Alto, the noise from the street is overwhelmingly loud, especially with the truck cleaning up the streets. This is a limitation you will expect in any apartment in this area. Lastly the bed was very soft which isn't my preference so sleeping was very difficult!
Overall I would recommend Rita's flat and would also recommend adopting a midday siesta in your routine to last throughout the hot sun and the loud late nights! It was a good experience and I feel like I know Lisbon a lot better.