I've been working in Korea for about four and a half years now as an English teacher, which means I'm a bit sheltered when it comes to Korean work culture since school environments are entirely different. Also, I'm not sure what kind of job you're looking for? However, I do have a lot of friends who work other gigs in Korea, so I can tell you what I gleaned from them.
Keep in mind that this is all for Seoul, where I live, but I imagine other places in Korea will be about the same.
1) Getting a job in Korea is an extremely difficult thing to do as a non-Korean. Even teaching English has major restrictions that exclude tons of people from applying to positions (the big one is that one must have a passport from one of the seven designated English-speaking countries). Why is it difficult? Well, why hire a foreigner when one can hire an equally qualified Korean who speaks the language and knows the culture? Plus, hiring a foreigner means having to sponsor visas, a process that a lot of places are not willing to go through just for one employee. Many of the people I know who work for corporate offices were transferred from their countries to Korea. Others were attending grad school or undergrad in Korea, worked as interns, and received full offers of employment upon graduating. Of the people I know who came to Korea and applied while they were here, a lot of them were told flat out that foreigners would not be hired. And if they were hired, they encountered a some racism, especially if they were not white. Same job opportunities might be possible if you are a fluent Korean speaker, have an impressive resume from your home country, and a top-notch degree. A good friend of mine did some journalism and editing work in the States, came to Korea to teach English, and then got a job as a copy editor for the English news department of a major newspaper here in Korea. It's possible, but it requires previous work experience, connections, and luck. There's also always restaurant/bar work in Itaewon/HBC, the foreigner friendly neighborhood.
2) Living expenses are a bit cheaper here than they are back in my home country, but there's still a growing problem that the cost of living is increasing while salaries stay the same. Still, you can probably save a lot if you have no debt (unlike me and my dumb student loans ㅠㅠ). The majority of your money will probably be spent on housing. Unless you do a share home situation with a ton of roommates, housing can be really expensive in Seoul. In Korea, when renting a place, you have to give a key money deposit (보증금). I'm looking for a new place to stay, so I can tell you that the average amount for key money is 10,000,000 won, or $10,000. That's for a one room/studio apartment. Monthly rent ranges from $500 to $700. It's that key money that's the killer. There are cheaper options: share houses; boarding houses; 고시원/고시텔. But they're definitely not as comfortable as having your own place.
Reading back over this, everything seems so negative, but, yeah, getting a job (depending on what job you want) can be really difficult for foreigners. I know a lot of people who are on working holiday visas---they work in restaurants, make up shops (usually in areas where there are a lot of tourists---it's a popular job for Chinese or Thai working holiday visa holders), and one friend even works in a travel agency that caters to Chinese tourists coming to Korea. But getting an office job in a Korean company is reaaallllyyyyy hard. So, I guess it just depends on what you're looking for?
