Rolf has a great apartment and I would encourage you to stay if a central, beautiful place is what you are after.
The apartment does not have an external sitting area, however the amount of windows allows for a beautiful, breezy place to sit/ cook / have a wine.
The experience is not the normal Airbnb experience as you are not hosted - a key pad allows you to enter and leave.
We had a relaxing and calm week in Lisbon - we were able to enjoy the city and its delights as well as easily pop down the hill to the train and head to cascais beach for swims.