Pros
If you work in HQ in Seoul your salary and benefits will be above average along with plenty of opportunities for training. Promotions come on a fixed structure of years worked along with several intangibles such as vacations taken/projects worked/manager reviews so you will always have a clear view of where your career will land.
Cons
If you work anywhere outside of HQ or if you are not Korean you will feel a low ceiling and obvious divide between the HQ workers. HQ also has a strong influence on the branch offices in regards to culture, pay, work hours, which will often not be align to Western office expectations. There are many regulations, policies, and roles & responsibilities but are more for show than anything. Executive / Senior management is very intelligent and have developed a strong and viable business model to have a moral, profitable operation in the United States. However those morals and business models seem to get lost in the execution done mostly by middle managers.