That was my first experience using Airbnb and it was really good.
About the host:
Thierry was very accommodating, pleasant and helpful. He even changed the check-in because of my crazy schedule and welcomed me with seasonal fruits and candies (isn't it great?). Thierry showed me everything in the studio and gave me instructions on where to leave the keys (he couldn't pick them up because I was leaving really early in the morning). He also had a lot of brochures and information about the city and recommendations on where to go.
About the studio:
The studio is small but very well equipped and really comfortable. As in old Parisian buildings, the bathroom in the studio is small but clean and functional. There is a well equipped kitchen with several supplies. The studio faces a courtyard, it has 3 windows from which you can see picturesque views of the city's roofs. There is a 1-person elevator, really helpful to lift your luggage.
About the neighborhood:
The studio is located north of Le Marais and really close to Place de la République: location is amazing. Pretty lonely by night but safe. It is close to 2 metro stops: Temple and Arts et Metiers (this one has to be one of the most interesting/picturesque metro stops in the world, check it out). You are pretty much connected to everywhere in Paris from there.
My overall experience was really good, Thierry was charming and helpful and his studio comfortable and cozy.