I had a great time in Cascais. The apartment is very tidy, modern and quiet. It’s in a residential area, you have a supermarket around the corner, but no cafes or restaurants. For that you have to go to the city center. There is a bus stop close by, but you might have to wait a bit for the buses to come and you need to waive them down! (I learned that the hard way).
In case of bigger problems or recommendations, I just want to point out that Claudia (the host) does not speak English or other languages than Portuguese very well. Currently there is a permanent room mate living in the apartment who can translate to Spanish and Claudia uses the translation function on airbnb to communicate. For me this was fine, and it should work as long as there are no immediate issues or you don’t feel the need to have long chats with your host.