Let's start with the good things about Guy and Vera's apartment: it is perfect for a romantic getaway. It's small, but the perfect size for two people.The decoration is relaxing mix between vintage motifs and modern furniture, which makes it really cozy yet very functional.
The bed is EXTREMELY comfortable, the lights turn off with a switch right next to you so you don't have to get up and each side has a sort of "simplified vanity" (a mirror and a couple of shelves) which makes getting ready easier. There were absolutely DELICIOUS cookies waiting for us in there too.
The location I would say, it's perfect, it's not too far away from the actual park, but it isn't far from the village either, which allowed to us to go to a supermarket nearby and get to the sightseeing spots easily. Beware, everything is terribly expensive in Sintra, so having a supermarket nearby is crucial if you are in any kind of budget.
The kitchen is very well equipped (the knives are amazing), it has an electric stove, electric toaster and a capsule coffee maker, plenty of pots and pans and pretty mats.
Now onto the bad: it's rather cold for the winter, it has two electric heaters which are not very potent, they will do the job, but you won't be getting home to a warm house, which takes us to the biggest issue of the house: the voltage.
If you are trying to cook and keeping the heater on at the same time, the switches will come down constantly. It took us a while to figure out what it was, we had to unplug everything, and even then it was hard to use more than one device at the time. This meant we took a really long time angrily cooking our first dinner, not very romantic.
Also, the shower. It works with a thermos, so you have to take pretty quick showers, again, not the most romantic or comfortable, but really eco-friendly though.
We highly recommend this location, but more so on the summer.