When I was a kid we had two exchange students. First we had a German boy who was great and then a French boy I detested. Overall it was a terrific experience both times. Even though I didn't like the French kid, I did learn alot of French (he refused to speak English for a while). My mom's kept in touch with them, and we visit back and forth once in a while. The German and his mom came out for my wedding.
I was an exchange student for a summer once. It was great, but health issues and home sickness kept it from being all I had hoped.
I think you're really lucky. I hope to be able to host students someday!