We were a little concerned staying above a train station, but given the location and the view, we decided to give it a try and we are very happy we did. This apartment is in a great location, with beautiful views of the ocean and just under the tracks to the esplanade where you are a short 10 min walk to the beautiful town of Cascais in one direction and Estoril and the Casino in the other direction. The small but cute town of Monte Estoril is just up the hill as well. The apartment itself is adorable. The owner is either an interior decorator or hired one because it is tasteful decorated and perfectly equipped with everything you need, including all modern appliances. The caretaker was wonderful and very responsive to any questions or needs.
As for the train noise, when the windows are closed (and icy-cold air conditioning is running) you can barely hear the train which stops running during the sleeping hours. So they did a wonderful job with soundproofing.
Naturally, the benefit of staying above the train station is that you can just roll out of bed and hop on a train to Lisbon or Cascais or any place inbetween. No need for a car unless visiting places off the train line. And if you have a car, there is paid parking right outside the door (free overnight).
Overall a great stay at a cute/lovely apartment. Great for a couple or a family of 4.
Enjoyed our stay!