We (5 persons) stayed in the flat for four days. We enjoyed this visit very much. The flat is big enough for five persons, if the restriction is acceptable, that one of these five has to sleep in the living room.
For four persons its comfortable.
The most outstanding plus of the flat is the view over the river - it is grand. The location is very central in the district Alfama with only a 15-20 minutes to walk to the Praça do Comércio or 5-10 minutes to Castelo de S. Jorge.
The flat service is friendly and flexible. A lot of recommendations for restaurants or points of interest are shown in a printed info folder in the flat.
As typically for these buildings, you have to accept, that the flat is not barrier-free - steep and tidy stairs - also in the flat itself.

But from us five - a clear recommendation!