When I joined Airbnb I was asked to fill a questionaire. One of the questions was "What impact has Airbnb had in your life?". I reckon my answer was literally "Ask me in a couple of months time".
It has been a short while now and I can say I AM LOVING IT!! I host essentially for the money: my flat needs some improvements my wages cannot cover, but the side effects are top: the people I have had around are great, completelly crashing my scary-dream expectations, the opportunity to share my inside knowledge of the city is a pleasure (although some the guests have proved to know way more than me), I once even got a proffessional guided tour to my own local museum (my host was a phd student specialised in Sevillian baroque painters), and (finally) my house is the cleanest it has ever been! Ok, not my room or the storage room, which are the way they have always been, but yes the rest of the house.
Can you ask for more? I cant recommend it enough.