My husband and I stayed there for 1 month while working remotely.
The place is spacious and is close from the center of Sintra, a few minutes walk from train station and supermarket and is very convenient.
The apartment is fully equipped with everything you would need and more :)
The only downside is that we could hear our neighbours and sometimes got woken up.
Aside from that, Fernando is an amazing host and pays meticulous attention to details. He even prepared us working chairs, so it was comfortable to work.