The location of this apartment is fantastic and seemingly in the center of it all in Paris. The unit itself disappointed in a the details, though: little things like the TV cable being unplugged, the shower door not closing properly, and the toilet seat being a bit off-kilter. The mattress was also tough and the pillows very uncomfortable (one is excessively big and the other excessively flat, leaving no happy middle). The street noise can also be loud, as others have pointed out, though this seems natural for a city and didn't bother too much.
I'm normally not one to point these things out in an Airbnb review, and each detail on their own would be fine -- taken together, though, it was all a bit distracting from our otherwise great experience in Paris.