We had a lovely stay at Pierre and Annette's apartment - they were waiting at the door to greet us right at 1 PM (which is when I had said we would arrive) and Pierre gave us a whole tour of the place and explained all the amenities. The apartment was spacious and very clean, the kitchen and bathroom were both super modern and the view from the living room was beautiful. Just a few notes (did not negatively affect our stay at all since we were aware of it prior to booking): on the 4th floor so you will need to climb stairs since the building does not have an elevator, no A/C but they do have two fans, weekend nights can be a bit loud from street noise if you have the windows open (I'm from NYC so this didn't bother me at all).
Overall, would highly recommend this place to stay - it was in the perfect location and allowed us to explore the entire Marais district on foot :)