It's not really free, it's just included in your salary, just like air fare. If I did go, I would probably be compensated more because I wouldn't require housing from my employers.

If you do decide to do this, make sure you do a TON of research. There are a lot of horror stories out there about employers taking your passport and not giving it back until the end of your contract (they're afraid you'll bone out), or robbing you of a month's pay because of some lame ass excuse, breaking your contract at 11 months so that you don't get your 12 month bonus, horrible working conditions, lies about where the school is actually located (urban vs. rural), etc. Make sure you do your research and find out exactly where you'll be going in China, what kind of school you'll be teaching at, and ask for contact information from previous teachers at that specific school to see what their experience was like.