I have indirectly used it before. My friend made the arrangements during a visit to Austin and I tagged along. I asked her how she picked which places to stay and she said that she only goes to places that has several (or more than several) positive reviews. She also request that they write a review about her (as a visitor) to help her future travel host trust her presence. We will be using another airbnb place next weekend.
In terms of the experience itself, the host told her where they left the key, we found it, let ourselves in, used their bathroom, shower and bedroom (which obviously had belong to their daughter at some point) and just let ourselves in and out of their house as we quietly pleased. They wrote a short little list of attractions in the area and left it on our bed, but they didn't change their day around to show us around - they had their own lives. We didn't see them except for the day we left. We didn't use their kitchen or food. I am not sure if it was an option (I never read the specific airbnb website details about the location), but I didn't want to do something to make the host feel uncomfortable. I was nervous about the whole experience, but felt more comfortable traveling with another friend.
I don't know the specifics, but it is debated among my friends if this practice is legal in some instances - like people renting out rooms that are not technically their own. That doesn't stop my friends from using it though, just more of a question if the website will be closed down at some point.
