It's the perfect airbnb experience. Nicholas was very helpful in allowing me to check in earlier than usual. The apartment was a decent size and very well equipped. The location is great, near 2 metro lines and walking distance to Montmartre. I didn't find walking 5 stories up to be much of an issue, and the only thing bad i could say about the place is that on one night, one neighbor was blasting music loudly until well after mid night. And that's got nothing to do with Nicholas's apartment really.
All in all, one of the best Airbnb I've even been to and I would highly recommend it for visiting Paris!