I felt comfortable and welcome in Matildes Appartment. I enjoyed that much. Matilde is an uncomplicated, relaxed person who likes to chat with their guests.
You can go by feet to the trainstation, the supermarket, cafes, the old town, s. pedro and sightseeing spots. Just have in mind that sintra is spreaded over different hills, so it might be a bit sweaty. But it is really nice to explore the small footpathes, you will find a lot of nice views.
My room was clean, that was most important to me. If you want to have a very clean accomodation you may find the shared rooms a bit dirty.
Also you should bring enough warm cloth to sintra in general and also to matildes place, because of the humid climate in sintra.