Pros
Good experience for novice engineers. If you recently graduated from University, then you have good opportunities to get the experience with real industry problems and challenges. Your area of expertise can grow quite fast and you can understand the basic principles about research management. The foreign employers are usually supported with housing, and the taxes in South Korea are reasonable. The Samsung is a famous brand, so usually, the experience in Samsung allows to find better job easier, and can be a good step to find a good position in different company.
Cons
Once you got your area of expertise, which is needed for your job (~1 year), the further knowledge growth is quite limited. It's hard to know the working environment because of language barriers. Lots of politics in relations (maybe the same for all big companies).
