I have rented Airbnb and other rental by owners for many years on many continents.​ This trip was three: Rome, Florence, and then Paris.​
Granted I do not know the "norm" for Paris, as this was my first trip, however my observations and opinion are for the most part general and should at least compare to Rome which I rated highly.
The Good:​
The flat was clean, cute, ground floor, was easy to find, and unlock procedures(*below) quite straightforward and easy to follow.​ Cute "happening" neighborhood with lots of dining, etc.
The washer/dryer excellent. The bath heater and towel warmer fantistic. Excellent appliances and with manuals-a nice touch.
Could be better:​
It would have been nice to have at least a day or two of coffee (that worked in the nespresso) and especially laundry detergent - one per day. We bought a minimal container and left weeks worth for future guests. I would have left coffee, but drank it all​ :-)​
The Paris "Free Wifi" code did not work on the 2 occasions I tried it. May have just been too far away.
The Bad:
Only two medium size towels-no hand towels.
"Cozy" in this case was far smaller than photos indicated, which had the ladder+heater removed and coffee tables which were not present. Misleading.​
There was no walk to anything under 30-40 minutes - mass transit requisite.
(*above)The details indicated we would get lockbox code 36 hours in advance. We received it whilst on the TGV 3 hours from Paris and an hour before the checkin time at 15:00 - This created some anxiety.
The loft, being very close to the upper flat stairs, would at time sound like a herd of elephants above.
The Ugly:​
Roaches. When waking/returning and activating lights, they would scamper out. Fortunately a can of spray under sink-hmmmm.​
The loft was fun, BUT:​
The anchor above was loose.
The loft frame needs a hand hold, cushining for knees to make the left turn onto the iron, and there was an appliance on the floor below so the ladder could not be completely hung out of the way.​
Mattress not flat/even, may need replacing.
Ladder needs at least a short rail on right at the top.
On one occasion my wife finished her night's sleep on the sofa after using the toilet rather than climb back up.