This is a fabulous apartment. It is in an amazing location near the Costelo and Alfama district with all it's little bars and restaurants. You can walk to most central locations easily from the flat.
The apartment is very modern, clean and beautifully presented. It is even nicer than it looks in the pictures. It has lovely views and a fab little patisserie next door. There is a tram stop right out the front (number 28 I think)
The hosts were amazing. Our flight was delayed and then our cab got lost so we arrived around mid-night. They weren't annoyed at all and even gave us travel tips and recommendations in the middle of the night. We had a little problem with one of the lights and they responded quickly and helpfully.
General advice is that the apartment is in a hilly part of Lisbon. The apartment is up a flight of stairs. So you do need good shoes and a healthy disposition.