Google Maps has always "worked" for years here. Over time, the government has become less restrictive on what information they are granted access. Now, you can access basic subway/bus routes. If you can't speak Korean, then you can't use the Korean map services which offer far more detailed information.

Google Maps can work for basic directions. BUT you do need to be careful as a lot of the romanized spellings don't match addresses or other English spellings.

The government's hesitance also has to do with "military sites and security concerns."

http://www.koreatimes.co.kr/www/news...33_208414.html