I had a very pleasant stay at Filipe's apartment. Everything was as described. As many people noted, you'll share the apartment with other guests. It was no problem at all during my stay. Everything was clean and well organised.
I really liked the location of the place. Although it is not exactly central in Sintra, it is easy to reach and very calm with nice views of the town and the hills. It's definitely a great budget-friendly option for a stay in Sintra.