Everything about our stay was lovely. Check-in was easy, Sofia was extremely communicative, the space is secluded, serene and quiet (didn't have any trouble with noise on the cobblestones). It's also naturally nice and cool when the temperature in the city is hot.
Sofia was an amazing, understanding and considerate host. She was so accommodating and kind when we (stupidly) lost her keys (twice!). I highly recommend this airbnb to anyone staying in Paris.
Also, Les Marais is an adorable neighborhood, we happily spent most of our time near the airbnb - OFB is a radical/artsy bookstore, there's an excellent creperie nearby, the park just up the block is charming and sunny.