I spend a bit of time in South Korea and can say this:
1) South Korea is similarly more advanced than the West in some ways and less in others.
Large transportation infrastructure in South Korea is among the best I've seen, both because it is so comprehensive and because it is so new. So for example, the Seoul subway is easily comparable to the NYC subway in terms of size and coverage, but feels much nicer because it's so much newer. The stations are larger, the trains are new, etc. Similarly, Korean rail is easily as good as the best you'll find in Europe. The National Highway system is comprehensive, modern and easy to navigate.
Communications infrastructure is fantastic, easily the best I've seen. Very fast high speed internet everywhere, great mobile service, digital mobile TV in the subway, etc. etc.
Some infrastructure is not as good. In the well developed parts of the cities things like sewage aren't a problem, but you quickly drop off the development cliff as you head away from city center. Public restrooms are infrequent and typically dirty. If they have toilet paper, count yourself lucky. (However, the tap water is considered quite clean and drinkable by world health authorities even if the locals habitually don't drink it out of decade's old habit when things weren't quite as good). Farm areas are like farm areas anywhere, lots of dirt and plants and animals, but because of the difficult terrain, bringing modern mass farming practices has been very difficult and has left rural areas very undeveloped in relation to what you might find in the U.S. or Europe.
There's a huge disparity in things like construction quality. Some areas have impressive, modern buildings. Some areas (particularly older areas built up in the late 70s early 80s) look shabby and have issues associated with shoddy construction.
2) Software in the South Korea is...not as advanced as in the West, but from the sounds of it, in better shape than in Japan.
There's a pretty thriving games industry that's as good as any average or better than average western developed games. There's also a pretty sizable contract software industry. Mostly Western firms who've setup shop to take advantage of highly educated developers and slightly lower pay.
Though the Internet is high speed, for various reasons, almost entirely legal (that would involve thousands of words to properly explain and would probably require a dive into South Korean Social Security law believe it or not), browser technology and techniques are stuck with IE6 era sites. This means lots and lots and lots of flash everywhere to make things look good. However, the design work is about as good as what you'll normally find in the west. Nothing spectacular, they aren't pushing the boundaries of usability, but there's a sophistication in the sites that makes them equivalent to say reddit or amazon.
Here's two of the most popular sites
http://www.daum.net/
http://www.naver.com/
I think one thing that helps is that the South Koreans have a strong tradition in graphic design and the arts that at least helps make things look pleasant even if the interfaces can be a little "off". But you can see it everywhere, mundane signs in the grocery store for example, are put together with harmonious color schemes and beautiful typography. It's wholly different than Japanese aesthetic (and Chinese for that matter), and seems to have made it's way onto the web more or less.
I've never really encountered encoding issues or the like, I guess most places have moved on to UTF-8.
Most people at home have older, less powerful computers, but laptops and netbooks are extremely common. Apple computers...I think I've seen one, one time. And *nix is almost unknown. iPhones are starting to get popular, but most people have phones that better work in South Korea since they also have digital TV reception (yes, it's broadcast over the air) and near field payment chips and such in the phones.
3) Facebook is not heavily used (if at all) compared to other social media sites.