The pros:
*The apartment is in a good location, it was within walking distance of many of the tourist attractions (just a 10 minute walk to Notre Dame) and it was easy to get to Metro stations to take you anywhere else you'd like to go.
*There are plenty of cute restaurants, bars and stores nearby.
*The lower level of the apartment was very nice, with good natural lighting, and there was a small balcony that was a nice place to drink a glass or two of wine.
*Louise sent us detailed instructions ahead of time on how to get to the apartment from the airport, which was a nice touch. She was very responsive throughout our stay.

The cons:
*The stairs! The description mentions the 5 flights of stairs, so we thought we were prepared, but these are quite brutal (particularly bringing luggage up and down) and we arranged our days in order to not have to climb them more than absolutely necessary. And we are a fairly fit family, so we didn't expect them to be such a big factor.
*The loft. We are a tall family and the ceiling of the loft was very low, so we had to crouch and crawl to make our way around without hitting our heads (which we still often did). There was only one narrow path on the far side that we could stand upright. My 11 year old niece was the only one who could maneuver it without much difficulty and she was often sent upstairs to fetch things on everyone's behalf. We'd also work extra hard to make sure we had everything we needed for the day before coming down.
*This is not necessarily unique to the apartment, but the showers were also very small. We had a hard time doing what we needed to do, even with our being relatively thin. Larger individuals may struggle with this.
*The neighborhood is safe and cute, but when we came back later at night there were a few bars showing rather explicit videos on the streets. This would not have been a big deal at all had we not had an 11 year old with us, who got quite the education!
*While this is not necessarily something you should expect, this was the first experience with AirBnB that the host was not there to greet us and provide some sort of welcome/orientation. I got the feeling that this is something she usually does though. I tried for a good 15 minutes to unlock the door before having to suck up international data charges and contact her for help, though she did get a neighbor over very quickly to assist me and give me a tutorial, which was appreciated.