The teaching position I am currently employed in happens to be the first my headhunter offered me. It is a job about an hour of transit away from downtown Seoul, in Bundang, teaching history and debating. My class sizes are capped at 8 students, and I teach from grade 1 to 6. I work from 1-9:30 from Monday to Friday, at an average of 5 teaching hours per day. I find the work enjoyable, and I have lots of free time to explore the city, do hobbies, meet people, etc. There is a lot to do in Seoul, and a good community of expats and Koreans who speak English. Getting around is no problem.
Food is slightly more expensive here than where I am from (Toronto, Canada), especially fresh fruit. The pay is pretty good, however, so one can live in comfort regardless.
My headhunter was very helpful throughout the application and pre and post flight process, always being there to answer any questions I had, and giving useful advice on what to bring and how to prepare. I'm very glad I got this position rather than one teaching English grammar, this is probably the best aspect of my whole experience. It is a pleasure teaching students who already have a good grasp of the language and can apply it to interesting topics.
If I were a new person applying, I'd make sure to take a good look at the class sizes, location, and subjects you are to be teaching. They've made a huge (positive) impact on my experience here.