This is a very clean apartment in a multiple-story apartment complex. It's conveniently located to the yellow line of the Metro if you're comfortable using that (and it's the best way to get around Lisbon). It's not close to much of what visitors typically want to see, but the Metro helps you get there efficiently.
Be aware that it is also right in the flight path of the airport's departing flights, so you have super-big jets flying overhead. You don't hear it too much once you're in the apartment if the windows are closed, but just be aware of that if airplane noise bothers you.