Historic building with modern furnishings, the flat is clean with thoughtful touches and plenty of amenities. It's in a great location in the old part of town, and the hills of Alfama are really not that bad - I would absolutely stay here again. It was easy to walk to other parts of the city, and there's a large supermarket close by. The best part of the flat is the view - it's right below the castle and it's nice just to open all the windows and look out across central Lisbon.
I stayed on my own and it would be perfect for a couple, but it might be a bit tight for six people. I would say anyone on the tall side might struggle with the loft bedroom as the ceiling is quite low.
In all, this is a wonderful base from which to explore Lisbon, the flat is central but quiet and I felt safe in the area.