The location is great. It is centrally located to the center of Paris, the metro, the Seine, to Notre Dame Cathedral, great walking. It's a fourth floor walkup in a 400 year old building; so the stairs may present a challenge to some people. The apartment itself is very cute and cozy. It is one big room with a lot of character, but don't expect much privacy.
They were exceptionally gracious hosts and we had a great time. We would definitely return.