We (my husband and I) stayed for a week in Guillaume's apartment and were so comfortable and happy.
It is wonderfully light. All the rooms in the apartment have large double casement windows with a lovely view of the trees opposite. In spite of the large windows there is very little noise because the apartment does not look onto the road.
The apartment is near two metro stops and so it is quick and easy to get to all the main galleries and museums and also the department stores. There are many restaurants in the area and several small supermarkets nearby.
Guillaume was a great host and quickly sorted out any problems we had. Like one of the other reviewers, we did have a bit of trouble with the internet connection, but Guillaume told us that he is planning to change the provider.
We would definitely want to stay in Guillaume's apartment again.