I stayed 1 month in the flat.
The location is amazing. Very close to everything you need to see, very quiet during the day and the night.
The flat is old and you can hear the neighbors but I guess it’s the same in all the flats in Alfama.
The big room does not have a window so it’s a bit shady and during the night a bit warm.
My main problem was the wifi connexion , so I do not recommend this place if you want to work. The connexion is so slow that you can’t make calls / zoom / download things (such as emails).
The balcony is great and the view is wonderful.