Aurelien's place is near Le Marais, which is a pretty cool neighborhood in Paris - definitely not touristy. His street has tons of restaurants and bars, which is good, but also a bit noisy. Like many Paris apartments, there's no AC, not even a fan. However, to counteract this, opening two balcony doors created an effective cross-breeze -- it was just a bit too noisy to do this when we tried to sleep. One of our two nights was very warm. The courtyard side was very quiet, though.
His building has a lift, which is great, as he is on the top floor, and after a long day of walking the streets of Paris, those stairs can be tough. His apartment is pretty sparsely furnished, but the mattress was comfortable and he's got a big floor couch.
Our main issue was communication. We've been using Airbnb in Europe for years and rarely had issues. However, we messaged Aurelien the day before we were to arrive (twice) with no response. The next day, a few hours before we left for the airport, we had to contact Airbnb. They called multiple times without a response. It got to the point where we had to cancel the booking in hopes of finding something else in Paris (this is on the way to the airport). Right then, Aurelien came through and we reactivated the booking. We agreed to meet at the apartment at 7. I told him that we do not have a phone that works for calling / SMS in Europe.
We arrive on time and he is not there. We try to find free wifi but there's no such thing in Paris, at least not this area. Finally, 20 minutes later, he comes out of the apartment. He said he'd called and messaged me (though I'd told him twice that my phone doesn't work in Europe) and that he was going to find us at the metro stop at 7:30 (which was not what we'd agreed upon). It was frustrating.
After that, things were fine. Aurelien was a really nice person, he did a great job showing us around, told us we could eat or drink anything in his apartment, use anything, gave us restaurant recommendations for the neighborhood.
My recommendation: If you want to stay away from the tourists in a more Parisian neighborhood, that's central and close to the metro, this is a great place. If you have SMS/calling in Europe, there should be no issues. If you don't, arrange to meet somewhere that has free wifi or message from the airport. Communication issues aside, things were good.