We definitely had a great stay at Delphine and Chea-Lie's place. It was a very clean and spacious apartment (compared to other 2-bedroom apartments in Paris). We were a family of 5, but the apartment can easily accommodate a group of 6 (two double beds and 2 single beds).
The apartment is minutes away from République Square which is a very nice and dynamic place with lots of restaurants and cafés. However, the street leading to Château d'Eau station is not clean at all (garbage everywhere on the streets) and has lots of closed boutiques (but you can always avoid that street if you want and go near République or near Strasbourg Saint-Denis area).
The apartment is close to Metro lines 4 (Château d'Eau station), 5 (Jacques Bonsergent station), 4, 8 & 9 (Strasbourg Saint-Denis station), but also a 10-minute walk to République Station where you can find lines 3, 5, 8, 9, and 11. There is an electric scooters (trotinettes) parking and a Velib (bicycle renting station) right in front of the building, which is extremely convenient. A quick tip: try to go right when you get out of the building, it's way closer to both Strasbourg Saint-Denis station and République Square.
Check-in and check-out were very smooth, and Delphine & Chea-Lie were very fast at responding to our messages.
Overall, we had a very good stay and we'd definitely do it again!