We stayed in this apartment with 3 of our boys (ages 17, 14, and 12) and really enjoyed the place. The apartment is large, clean, and had plenty of room for all of us. The beds were comfortable though the sheets felt starchy and somewhat itchy. The views from the windows were great and it was relatively quiet except for one night when crazy stuff was happening with late night revelers on the street. It's a bit of a maze when you first get there because of all the rooms and doors, but it was a really beautiful spot to hang and rest our heads. Having the A/C was also great because we were there during a heatwave!
The location cannot be beat; you can easily walk to so many other districts and downtown. The Elevador do Castelo up the street was a fun way to cross the street, so to speak. :) And there are soooo many great restaurants nearby. The easy/quick walk to the Alfama district was really great as well.
The only downsides, I would say are the fact that you need to go to a secondary location to get the keys and that the upstairs shower is pretty much unusable because the showerhead had to be held and, even when we tried it, so much water escaped due to the ill-fitting shower curtain. On the key pick-up, they do offer a car service that knows to drive you there then to the apartment, but we couldn't avail ourselves of it due to the timing of our flight.
All in all, we recommend this place and would 100% stay here again!