Cute apartment. Easy access to the Metro via Gare d’Austerlitz, but should be aware that this is still far from most of the sites in the city.
Lack of AC in the apartment is a challenge in the summer months, but the two fans provided helped.
The two beds in the loft are probably designed with children in mind, but I would advise against putting any young children up there. The staircase is very steep with narrow steps - difficult for an adult, outright dangerous for children.
The rental agency offers ground transport to/from the apartment, but I would advise against it: they cancelled our transfer hours before our arrival, leaving us with last minute scramble to find a ride and no offer to help. You’re better off going straight to a taxi company - price is the same and things are under your control.