This place is perfect location for exploring Lisbon. The view is lovely, the space is unique and it's a great area to walk around. There are a few great overlooks close by, as well as the subway, the tram and many adorable little stress to explore. There's a great Fado place few doors down, too!
While it was not a problem for us, I'll say the walls are very, very thin and you can hear other apartments and the outside as if they were right next to you. If you are a light sleeper, or want to sleep in, this might not be your best option.
Also, if you are going to take a taxi or Uber, best to be dropped off or call them from the bottom of the hill or up the stairs, as cars can't get directly to the place.