Me and my girlfriend stayed over at Quentin's apartment for 4 nights. let's start with positive points : it is in great location, next to the metro station, with plenty of bars and restaurants around. That's where the positive points ends and negative points starts:
The apartment as a whole is not very clean. The bathroom, toilet and kitchen are quite filthy and we found this pretty appalling. The bathroom faucet also leaks quite loudly, which you can hear at all times in the bedroom. Quentin also left quite a angry note on the bathroom door, demanding that we wrapped a piece of string around the faucet after every use, because he did not want to bother to fix the issue properly.
If you are a light sleeper, forget about booking this apartment, our room was next to the bathroom and another room, which had very noisy guests. Also Quentin, on one night decided to take a shower at 2:30AM and he was very noisy, banging doors and not considerate at all. You can also hear the noise from the street, over 4 nights, we had maybe 4-5 hours maximum of sleep per night.
We do not recommend staying over at Quentin's place whatsoever. There are plenty of good rooms in Paris, but this place certainly isn't one.