We were 14 friends and there was plenty of space for all... there are only two sofas , so the majority of us had to sit at the table and chairs , slightly less comfortable but no big problem.
We were there only two nights so we had minimum luggage , so it was fine walking up the two floors with small cases as there is no lift.
Anyone with heavy or large suitcases may find it difficult.
The location is great... lots of nice restaurants and bars in easy walking distance and supermarkets...... a nice bar just under the apartment too.... and of course the main areas of Rossio , the Time Out market and main station of Cais do Sodre easy to get to.
A lovely stay in the lovely city of Lisboa.