We had a wonderful stay in Sintra and the apartment was the perfect place to get back to relax with room for the kids to play. With our kids (5 and 3) the walk to the old centre was still a bit of a challenge, but if kids are older or especially good walkers you could just walk into the old town. Supermarket around the corner and one a little further, but with a large playground. The kitchen also well equipped to prepare complete dinner dishes.
We parked our rental car in the street across with no parking charges.
I would definitely recommend it to others!
The only downside is that our travels from the airport went so smooth that we arrived half an hour too early from Lisbon for the host to arrive. As it was already 21.30h this was a bit uncomfortable. Keeping in good touch with the hosts is important as they don’t live in / near the apartment in order to welcome you in time.