I spend a month in Manuela's flat and I very recommend it.
First, the location is very good because it's situated not far from the center, ocean and Panteon which is famous Lisbon building and also near the park with a beautiful view. There are also many restaurants nearby.
Second, the flat have modern kitchen, big bed and space upstairs. Maybe not so big but it exists :)
There are also some disadvantages like very steep stairs to the flat so it can be hard for people with legs problems to go up the stairs and you need to take this into account.
I especially want to emphasize what a good hostess Manuela is. First of all the communication was very good and she met us personally when we arrived. Manuela also helped us with our bag and bought some food for us for the breakfast because it was late and nothing worked. It was very nice from her side and very unexpected. I think she is the best host we ever met on Airbnb and we are very thankful for her hospitality.
So if you want to stay in Lisbon I very recommend Manuela's house.