Another Asian metropolis. All of my relatives save for my great aunt live in South Korea, most around the Seoul area. I’ve been here many times with my immediate family, and last year I spent a month by myself.
Being alone, I had to rely on the subway for most of my transportation. And though it’s often really crowded (unfortunately at almost all times of the day) and very hot in the summertime, it’s really the best subway system I’ve ever seen. It’s clean, very fast, and in hot weather stepping onto the heavily air-conditioned trains is a blessing.
The people in Korea aren’t one of the most hospitable, I’d say. As in a lot of big cities, there are a lot of self-important businesspeople, crotchety old folks, and plenty of obnoxious teenagers. They can (though this is a generalization) seem very cold and selfish (unless they’re trying to sell you something), but it’s just how they are in the city, in public. Don’t get too unnerved.
English translation on signs is really helpful, though not always grammatically correct.
You should really check out all the big places, if just for the shopping. Myungdong, Namdaemun, Dongdaemun, and all of those other major shopping areas are often packed with people but excitingly so. There’s a lot of great stores in Korea, including Migliore which is a huge multistory ‘mall’, with lots of individual sellers with amazing clothes for negotiable prices. Don’t be afraid to bargain, because like everywhere else, sellers try to milk foreigners of cash.