This is a really great apartment, very stylish and comfortable, and immaculately clean. The location is convenient, with a few grocery stores, a supermarket and plenty of cafes close by. For travel, there are plenty of buses, you can walk, or head to the metro, the closest station being about a 15 minute walk. You can easily get to the Bairo Alto district - its a really nice walk and Bairo Alto is great for cafes, restaurants, shops, bars and all those good things.
Everything inside the apartment works well, it's very comfortable and there are some nice views. Being on the flight path to/from Lisbon airport means that there are regular planes flying over the apartment, so bring earplugs if you're a light sleeper. However, they do stop over night.
The hosts answered all my questions, so no complaints there.