Did it for 6 years, but it was a long time ago…
Good side:
* Being able to live abroad and meeting “real” people, not just resort staff out to make a living.
* Relative freedom to change countries when you get bored (relative in that getting a job in some countries can be hard)
* Loads of other 25yr old teachers means a great social life.
* Teaching, at least for the first couple of years, is fun. Changing country freshens it up for a while, too.
Bad side:
* Teaching the 1st conditional year after year after year gets dull, fast.
* The wages are pretty poor unless you do loads of hours. It’s a bit like a student lifestyle, great fun but you might find you grow out of it.
* Limiting in the end if you’re ambitious / career minded. (I’m exaggerating a bit: you can move into proper school teaching, although the lack of a formal kids qualification can be a problem.) If you’ve got a degree and you plan to use it at sometime in the future be aware that your fellow graduates will have a 2/3/4/whatever year headstart on you. (Again, this may or may not be a problem)
Neutral:
* You might find yourself, 14 years down the line, living in a foreign country with a foreign wife, mortgage, kids, dog and cat. At least I did 🙄