I could not fault Sylvia's place. Firstly - the rooftop is nothing short of sublime. Sitting up there in the morning and evenings for both sunrise and sunset with a coffee or a glass of wine watching the boats pass has become a daily ritual. It's calming, beautiful and ever-changing. The main terrace is also perfect - I have been working out there every day with expansive sky in front of you it's hard not to feel happy there.
The area itself is about 10 minutes by train into Lisbon city and 25 minutes to Cascais, so you are in a perfect location to visit both. As reviewers have said before, it is a 'local' area - so no, you may not find a hipster cappuccino right on your doorstep, but you will get many friendly neighbours willing to have a chat in Portuguese, and all amenities close, if you look for them.
Sylvia is a lovely host and is always at hand for anything that's needed.
Note the apartment is on the 4th floor, so the extra bonus is a workout for your quads ;-)
Highly recommended.