The appartment is tiny but well equipped. Great shower, very nice after a long day walking the streets of Paris. Not spotless but clean enough. The sofa bed was fine for me but rather uncomfortable for my man (1.90m/100kg).
Isabelle was very friendly and answered all messages before our stay promptly, although when I emailed her during our stay about the heater she never answered.
The location is really good, quiet, very close to a beautiful park and with good shops and restaurants nearby. Do go to the small Vietnamese restaurant at the end of Rue de la Villette; the food is wonderful and the price good.
The one thing that was really not ok for us was the bedsheets. Very worn and almost all buttons were missing so we ended up with a half-covered duvet every night.
Considering this I would still defenitely recommend the place unless you are tall and/or heavy built :-)