My son and I had a great 6-day stay in the apartment. Our host (Niels) was very responsive - easily reached by email and phone - and very accommodating of our requests (e.g., early check-in).
The apartment is quite comfortable, quiet and we felt at home. We used the kitchen for preparing light breakfasts.
The apartment is located in the Latin Quarter, very close to public transportation (metro, RER and bus) which we used throughout our stay. Niels emailed recommendations for sites to visit in the immediate neighborhood and a great area close by for some great small restaurants.
Our host was away most of our stay but quite communicative and left clear instructions for leaving the key on our departure.
We would definitely recommend this apartment to anyone visiting Paris for a few days who wants to be located in an interesting and centrally located neighborhood -- easy to get to tourist sites and things to do/see nearby. Thank you Niels for the great stay.