We stayed at Sophie's apartment for 3 nights during our stay in Paris. The apartment is exactly as you see in the photos. A very comfortable lace in an amazing location :)
1) The apartment is less than 2 min walk from Metro Station 'Villiers' which serves line 2 and line 3. It took us about 10-15min in train from Gare Du Nord (Eurostar) to get to her place. There are a few buses (within 200m) that take you to Montmartre/Sacre Coeur (10 min) & Opera/Gallery Lafayette (15 min) in one direction and to Arch de Triump (10 min) & Eiffel Tower (15 min) in the other direction. Notre Dam, Latin Quarter & Louvre can be reached by bus/train and took us around 15-20 min to get to them. So the location of the apartment in terms of transport is pretty good.
2) What I really loved about the apartment was it's the area/suburb it is in. There's a nice daily market 100m away that has cheese/wine/patisserie/supermarket/pharmacy/ATM etc. we got fresh produce for breakfast in the morning and took some stuff for picnic near Eiffel Tower. The area was safe even late at night and the best food we are in Paris was at the local french restaurant right on the same street as the apartment.
3) Sophie was very helpful and allowed us to leave our bags at the apartment on our lat day so we could continue exploring paris till evening without chugging our bags. She leaves this wonderful map for you that has all the famous sites highlighted saving you a lot of time and was extremely useful for navigating from the apartment to POi and then from one place to the other.
We would definitely recommend her apartment. Love the surrounding and hope we get a chance to visit Paris again and stay there.