The apartment is great! I stayed there for four nights while working in Lisbon. The location was ideal for me, with so many cafes and restaurants nearby. There are also a number of shops for groceries too.
It's close to a lot of the tourist attractions, plus a short walk to the train station. It's easy to get to in a taxi from the airport.
I was concerned it might be noisy at night as it's in a popular, lively area, but the double glazing and window shutters made the apartment very quiet. It was also hot while I was there, so the air conditioning was a real bonus. It has all the amenities you will want and is furnished in a stylish but comfortable way.
Entry when you first arrive is done via an app on your phone. This was my only concern as I didn't have data in Europe, but Patricia sent me the wifi details so I could connect that way.
I'd definitely recommend this apartment if you're visiting Lisbon!