We stayed at the apartment for almost two weeks and it was the perfect place for us. The location allowed us to walk to all the main tourist sites and the metro and Rossio train station (for day trips to Sintra) are also easily within walking distance. We were close to a number of grocery stores, restaurants, parks, etc.
Inside, the apartment was well equipped. The kitchen was probably the most well-stocked kitchen we've seen in an Airbnb and included all the equipment we needed - including a washing machine. The bed, although small, was very comfortable and we were provided with lots of pillows. The internet is reliable and fast.
We appreciated the quality of the furnishings and the live plants that helped the place feel like home. As others have mentioned, it's Lisbon, so you have to walk up a hill to get the apartment and walk up some stairs to enter the apartment itself. If we return to Lisbon, we would definitely want to stay here again.