sounds as though you will be in one of the larger cities then.
I lived there 10 years ago. It is a very safe country, very little crime, with great public transport and it is fairly cheap. Books are expensive, and western food can be expensive to buy fresh. You often have to buy it in department stores.
It is a patriarchal society; girls look after their parents and the home and aim to be fashion designers(!) dentists, teachers, nurses. The US army has a highly visible presence and there is a level of simmering discontent as the soldiers are generally young and known for their drinking.
In Korean schools, kids study from 8.30 - 3.30 and then go study schools for further classes until (depending on age) 9pm at night. They also study until mid afternoon on Saturdays. There is a lot of pressure to succeed from a very young age.
There is a double standard with regard to employment- Koreans often get fired with no notice and cannot protest, whereas International employees get great benefits- better money, more holidays etc etc.
People are private- you would tend to make few Korean friends, and in the year I was there none of my colleagues were invited to a Korean house, so it pays to build good ex-pat friendships.
Population density is very high, (50 million people in a small country) but there are some lovely places to get away if you can arrange transport.
Family is very important and in many families (though many women work), it is a bit 1950's in division of labour, and certainly 1950's in terms of social and sex education - if a girl kisses a boy, she would expect a very serious relationship. Sex=marriage.
Korea is a great place to live well, and it is incredibly easy to learn to read Korean (much harder to understand it and speak it fluently), so if you know what a few key words are you can manage quite well. English is widely spoken.
Hope this is useful and good luck with your decision :)