I spent two months at this location, and it is very recommendable. The location is great, the communication was great, everything you could need was there and it was very clean. Also the internet connection was very fast and stable, which helped for doing Home-Office from there.
The connection to public transport is also really good, Santa Apolónia is just a few minutes away by foot. From there one can use trains, busses, or the blue metro line right to the center of the city.
The apartment is directly in Alfama, an older and touristic part of the city, with lots of sightseeing and restaurants close by. Despite being very touristic, there is no outside noise in the apartment.
The apartment itself is generally a bit on the smaller side, perfect for one person, or alternatively for two people for a shorter time.
All in all I can very much recommend the apartment, and would gladly come back!