I returned only last week from Korea, where I had been for just 9 weeks. I was supposed to be in the country for a year, teaching English to children aged between four and sixteen. Like so many TEFL jobs, you work just 25 to 30 hours per week.
Employers really get you interested by offering free flights to wherever you choose to teach, free single accommodation and decent pay. In Korea, I was paid the equivalent of $2,000 a month for doing not very much.
But the novelty quickly wore off and I actually ran away from the school and returned home. I wasn't doing anything more than babysitting, the accommodation was filthy (damp and mouldy) and the staff at the school were not especially friendly towards me.
By leaving so early, I should have paid the school for the flight that got me out to Korea, but I chose not to.
Lots of people do have pleasant experiences in places like China, Taiwan, Korea, Thailand, Japan etc. and I'm sure that you would also enjoy it, but be sure to shop around for the school that sounds right for you. Don't accept the first job that comes up (one thing you'll notice is that EVERY school will offer you a job). Spend a few days doing some research into your school and insist on having email addresses and telephone numbers of the current foreign teachers. After all, they are the best people to tell you how good or bad a school is.
I, however, wouldn't recommend the experience!