My friends and I (three adults in total) had a great week staying in Xavier's apartment. The view is awesome from up up high and the location is amazing. The Montparnasse neighborhood has a ton of restaurants and metro lines 4 & 6 get you to many of the tourist destinations in Paris.
The kitchen is quite functional. We easily cooked large breakfasts each day in the apartment without issue. There is elevator access from street level, which is notable in Paris. Xavier was communicative and helpful throughout the stay. We would absolutely stay again.