It is a shared space, very small and not private at all. A bit pricey for what you get, I can imagine it is very uncomfortable if the place is fully booked. Men and women have a separate room.
Positively though: it is good value for the city, the location is amazing (for backpackers, don't bring your children) located right next to a subway station that will take you directly to the Eiffel tower, and nearish to gare du Nord (15m walk) which links to the airport. The best things about the place are that it is super clean, and that the host responds almost instantly all the time.