This apartment is a gem. The location is great, just south of the tip of Île de la Cité, but high and hidden enough to be totally quiet, with a great view. It contains all one person or a couple needs, it's appropriate also for longer stays (I stayed for 6 weeks). I do recommend it!
As often in France, the apartment could be cleaned a bit better. But no worries, nothing bad. Also, I am pretty certain it's not 50 m2 but rather closer to 35 m2 (but that this didn't bother me at all). The living room is as in the pictures; however, as the apartment is facing north, I wouldn't call it very bright. Also, the collection of broken or semi-broken chairs could be removed from the apartment.
The communication and check-in with the agency IntoParis were very good.