My wife and I stayed with our 2 daughters for a week in Julien and Cecile's apartment.
The apartment itself is beautiful and very spacious.
Cecile was waiting for us in the apartment with very clear explanations (and even post-it notes on the TV and remote controls explaining everything) and a bottle of wine...
Location is extremely convenient, 10 second walk from Temple metro, and 2 minute walk from Republique (downside is that it is facing a main street).
Just across the street there is a Monoprix supermarket, which is extremely convenient.
The apartment also has everything needed, from an excellent oven and dishwasher to washing machine and dryer.
It is a 10-15 minute walk to the heart of Marais (Rue des Francs Bourgeois) or to Centre Pompidou, 5 minutes to north Marais and Marche des Enfants Rouges.
In general, it was an extremely good experience.