My wife and I spent a few days in this apartment during our stay in Lisbon. The apartment is quite narrow even for a couple, but absolutely well equipped and furnished with style, we found everything we needed and even more! It was a nice stay.
I suggest not to get to Lisbon - and expecially to Alfama district - by car, and to travel light avoiding big heavy luggage. This because you would carry it upstairs in very narrow alleys to get to the apartment, and that's not that easy!