Let me begin by saying that the following issues are mostly fixable -- will just be a matter of if management/host can communicate the right information better and in a timely fashion.
Our stay at this apartment was unfortunately tainted by the difficulty with the codes to get into the passage where the apartment is located. The apartment lies with a Passage (essentially a passageway that cuts through the middle of the street that is lined with stores). While the idea was interesting, what we were not made aware of prior was that we would need a code to get into the passageway before we could to the door of the apartment. Additionally, there are three entry points to the passageway and apparently the code could only be used on one of those doors after hours.
The code changed during our stay, and we were unable to get into the passage 3 nights of our 5-night stay (which we had to find out the hard way). Two of the nights, we got lucky with people coming out (walking their dog, leaving for a flight). The third night, I was not able to get into the passageway at all and was unable to stay at the apartment that night. I did test the code prior to closing hours to test the new code and had sent a message to whomever was handling the reservation. We did not receive an answer back in a timely fashion to any of the messages sent (had sent multiple messages throughout the trip). The day after being locked out, I had to call around 11am and try to speak to someone. Again, the only way we got in was through one of the stores that opened early that day (most stores have an entrance into the passageway as well as the street).
I was offered reimbursement for the one night we did not get lucky, which I am still waiting on the management team for more information (though we were not able to get in multiple times). However, it hardly makes up being locked out of an Airbnb when on a vacation in a foreign country, regardless of what hour we returned.
The apartment was up about 3/4 flights of stairs, which posed a bit of an issue getting luggage up as the steps were quite steep/narrow. Then, when entering the apartment, there is another set of stairs into the kitchen area. Clearer instructions on checking in/misc items (how many flights of stairs to go up, how to properly lock the door, etc) would have been helpful.
That being said, the apartment had a nice kitchen/living area and was clean. We had no issues with electricity, hot water, etc. The furniture was comfortable and the set up was minimalist but atheistically pleasing. The ceiling of the lofted bed area was a bit too low for my liking (I'm about 5'3" and I hit my head on the ceiling every time i went up). The real issue here we had was that stairs to the bed had no railing. We didn't feel comfortable going up and down the bookcase-like stairs to the bed, so we ended up sleeping on the couch (which was actually very comfy and fit the both of us). That might be a personal preference but didn't want to risk injury while being groggy and dazed when walking down in the middle of the night/morning.
The area the apartment is located is really great - restaurants/shops/the Louvre were walkable.
Some advice to those who are decide to stay here - if you are planning on having some late nights while in Paris, double check the code and know which door to use after hours.
Really wanted to love this place, and atheistically we did; but there were too many logistical issues for us to return for a second stay.