"Location, location, location" is often considered the three key features for real estate, and that is the first positive thing I'd say about Christine's flat. It's virtually across the street from the Beaubourg/Pompidou Museum (You can see the top of the structure from the window in the apartment.) and close to all the sights of the Marais. The flat is equipped with everything you could want: refrigerator, washing machine, stove, dishwasher, microwave, plenty of hot water. It only lacks a drier, but the drying rack worked very well.
Christine welcomed us warmly to the flat and provided us with a loose leaf binder showing nearby shops -- bakery, cheese shop, market -- as well as recommended restaurants in the neighborhood. We found enough sources for excellent food within a short walk that we could eat a lot of meals at home.
Two minor drawbacks to the flat: you've got to climb 60 steps to reach it. The stairs are wide and there are several landings but you've still got to make it up those stairs.
And the furnishings in the flat -- especially the carpeting -- could use some updating.
But all in all this is an excellent choice for a stay in Paris by a couple who want good value, a chance to be centrally located, and the experience of living in a historic building in Paris.