This apartment is located in the heart of back-packer-land, which is a rundown area of Lisbon with plenty of derelict/abandoned buildings (which in a way, adds to its charm). You’ll see plenty of drug dealers and users, and will be asked to buy drugs on a regular basis (multiple times a day). In saying that this is also the most exciting part of town, right behind the TimeOut market and within walking distance of all major Lisbon historical sites. And the drug dealers aren’t dangerous.
The apartment itself is a gutted and renovated building. However, the renovations were done a long time ago or not very well, and there is a lot of minor broken fixtures, etc. that have been left in-repaired. The floor also creeks intensely, and you can hear the neighbors walking above and street noise from outside. The old plumbing also fills the apartment with the familiar and unpleasant “ancient plumbing and sewer system” smell. I think the name of the apartment and the description is quite misleading. I would personally describe it as a 3 star apartment.
Other than that we had a nice enough time. You definitely get used to a lot of these things. But if these are aspects of travel that don’t agree with you then I would recommend you look for something in the more well-kept parts of Lisbon.