Unfortunately Martin and Roberta where away during most our stay. This is something we wish we had been told about before getting there. We were disappointed that we could not enjoy the great hospitality mentioned in the comments.
Also, we struggled to get to their place on the first day, and the bikes mentioned in the desciption were broken.
Apart from that, we had a good time in Sintra. The area is nice and there are lots of things to do.