About the only downside Iv'e experienced so far is that I have to wash sheets all the time (most people stay with us for 2-3 days and since we now have between 70%-100% occupancy thats a lot of sheet washing.
I'm also about to go to Paris and the value proposition of airbnb there is even better (try hipmunk's hotel search in Paris). We are staying in a private entire apartment on the seine with a view of the eiffel tower for about $130 a night.