I rated this a little lower for a few hiccups during our stay. But overall no major complaints, especially if you are aware of a few things beforehand (which this review hopefully will help with).
First, you will need to download an app to get the digital key. For security purposes you will receive the details needed only the day before. Not so big of a deal as WiFi is accessible throughout Sintra, but it is not as stress-free as as the usual self check in where you just need a code.
Second, I guess you can tell from the pics but it is not mentioned explicitly but there are stairs. We had a lot of luggage and did not enjoy the surprise of finding out it was on the 3rd floor (by US definition so not counting the ground floor).
Third, no luggage drop off. I am not holding this against them as they did not advertise as such, but with the strict check in time I would have expected the room to actually be ready. Instead we arrived after check in but before the room was cleaned. The cleaners arrived shortly after we did so it wasn’t a huge inconvenience though.
Lastly I get the fully automated/hands off approach, but this is fairly inconvenient at times. I was not getting responses, sometimes within days and often times I needed to ask again the following day for an answer.
With all that said, the place is very quaint and the location is pretty unbeatable. Many practical things in the immediate vicinity - a minimart, a fun miradouro, many places to eat, etc and the front door is a hotspot for transport (tuktuks, taxis, bus). Also an incredible view of the castle in the distance from the terrace. All for a very reasonable price!
Would definitely stay here again, especially knowing what I know now. And would still recommend to others.