This apartment is modern, clean, and convenient. We stayed in it for 8 nights with two adult children, and everyone was very comfortable. It is right downtown in the Baxia area. It is close to a Metro station, the #28 tram, and a just a few blocks from the Rossio train station. If you will have a car for part of your stay, the parking garage is a definite plus.
The apartment does have an elevator; however to access it, you either end up walking up quite a few stairs outside or a large cobblestone hill unless you come in through the parking garage. This is pretty normal for Lisbon, but if someone has accessibility issues, this is good to know.
The only negative for us was we stayed over a week and could have used some extra towels, tp, etc. Hopefully the owner will be responsive to my comments on this.