We loved our stay in Sintra! It is so close to the main areas.
If taking a taxi, we recommend being dropped off at Palacio Nacional de Sintra since the back way can be really long. It took us like 30 minutes to arrive (because of small and one-way streets) and if we had been dropped off there, it would have been 5 min. after getting off at the palace, it's 3-4 minutes walking. If you have huge luggage maybe this isnt for you, but for us it seemed simpler.
Very close to a lot of restaurants.
The apt itself was cozy. The kitchen was very cute and we could've cooked meals if we wanted to. The bathroom is also very cute. Follow instructions for how to get hot water listed at the bathroom bc it will go out in the middle if you don't prepare ahead of time. Once we followed the instructions and turned on the sink, we had no issues.
We only had 2 guests, but in theory you could have someone else sleep on the sofa bed, but I can't speak on whether it is comfortable or not.
We arrived before our check in time and the host was super flexible and told us instructions on how to leave our luggage at the reception. they have lockers and you don't need to be helped by anyone. This was a huge help as Sintra is not fun with luggage!
Thank you!