I do not have a personal experience but 2 family members who have done it. My baby bro did it for a year in South Korea after getting his TEFL state side. He had experience as a sub teacher in Boston and LA. He went with an agency and was placed in an after school program for six to ten year old kids.
The upside: he really enjoyed his students. He was impressed that six and seven year old students could diagram sentences, in English, at a level that surpassed most middle school students in the USA. He liked his coworkers allot too...most were Canadian, Australian and Kiwis. Being 30 at the time, he was one of the older expats at the institute. His apartment was modest, but acceptable.
Downside: many parents,who are paying out of pocket tuition for the program, were demanding to the point of being unreasonable. Any dissatisfaction with their kids progress went straight to the director, and of course the shit rolled downhill to the teaching staff. Also there was not much time off during his contract....a few days here and there...but not enough to explore the continent. He did his Grand Tour of Asia,Australia and New Zealand in the two months after his contract ended.
Second is my sister in law's brother and his wife. They are in a 'town' in China of about 2 million people. There is no airport...they fly into Guangzhou and take a six hour train ride. Being in a remote area of the PRC they do not have many modern amenities that are available in say, Shanghai. Both have been teaching business English to adults for six years and love it. They are now fluent in two Chinese dialects and will give birth to their first born child in China this October.
If you want you can pvt me and ill get the name of the organization my bro used. I can also ask my sis in law for contact info for her brother.