Margarida's place is located near Palacio Ajuda (very impressive building) which is enough away from touristy Belem to put you away from the tourist BS. It's easy enough to get down to tourist stuff with a bike ride (or a ~30 min walk). I appreciated the quiet and ability to live with normal people. A small supermarket, churruscaria and more are within about 10-15 mins down the (steep) hill. You can take a bus if you want, but I enjoy walking the hills.
Margarida is a complete sweetheart. I told Margarida that good internet was important for me as I had to work in the evenings. When I arrived, the router was in my room and a cable there for me to plug into. This is often better than wifi which she had also. This is one example of how I could see Margarida took a genuine interest in making everything as good as it could be. Margarida is also a former professional chef and it is clearly still a love of hers. If you have the opportunity to taste her cooking I suggest you do. I tasted some of her Bacalao (Cod) dish, which regrettably I have forgotten the complete Portuguese name. It was yummy :-)
This is not the Hilton. There's one bathroom for the whole house (I had to wait only once) and the house dates to the 1940's. Personally, I appreciate the style and enjoyed much being there but if you're a "high maintenance", "everything must be perfect and new" person then this is not the place for you. On the other hand, if you appreciate "real" and don't mind turning off the toilet for the shower to have enough pressure, then you'll be fine and perhaps even love it as I did. I had a great time and attribute that 1/2 to the nice place to stay and 1/2 to Margarida :-)