This apartment is a really nice place to stay in Lisbon.
The location is great, very close to the central squares and various attractions. Just 500m away is the "Time Out Market", a big food court with fancy food for every taste.
If you arrive to the apartment on foot with a heavy luggage, it's probably easier to walk from Baixa-Chiado subway station. Take Rua do Loreto / Largo Calhariz street first, and turn left only when you reach R.Mal.Saldnha. This way you won't have to go up and down several times.
The apartment itself is cozy and clean, the bed is comfortable, the furniture is nice, the kitchen is well equipped, and the entire design is interesting and unusual. There was an air conditioner enough to make the apartment warm during our stay in December (with 10-18 degrees outside). The electric radiator in the bathroom was also handy for keeping the towels warm and dry. There was enough hot water to take either one very long shower or two short ones in a row.
Perhaps, you might only feel a bit uncomfortable if you either tall (as some parts of the apartment have pretty low ceilings, e.g. the bathroom) or really hate stairs (the way up to the apartment is steep, plus there are a few extra steps up and down to get to the bathroom).