Pros
They take care of you and pay you on time. They also give you part of fridays and the weekend off as well, depending on your role. If you're a religious teacher then you have to attend certain things on Saturdays. You get around 3-4 days off every term (every 2 months).
Cons
It really depends on your location. I worked at two different locations and one was not great, but the other one was pretty good. If the director communicates with you frequently and seems to genuinely care about you and your work then everything should be fine, but if not then it's going to be a pain. You don't really know where you're going until the last day of training.
In general the main office is incredibly disorganized and don't really listen to feedback very often. Even during training I wasn't informed of practical things like how to conducts test. I can see that they're trying to change but it doesn't seem to work. I felt a little bit overworked and only the positive environment kept me going. If it wasn't for the people around me, I don't know what I would've done. I love Korea but working in Korea is just really stressful all around.