I had it done in Incheon, and it's been 4 years since I got my braces off. It's maintained well and I'm satisfied.
I searched and went because I wanted to have it done by an orthodontic specialist, and there was no overtreatment. Another doctor there took care of all my cavities and wisdom teeth too, so it was nice not having to go to another clinic.
For orthodontic treatment, make sure to look for a specialist before doing it..