While Google Maps in Korea has been improving, it's still very limited. Additionally, since most locals don't use it, the information on places (restaurants, etc.) is minimal and often out-of-date. Therefore, if staying more than a couple days, it would be best to use the Korean navigation apps, Naver Maps and Kakao Maps, which both have English versions. To learn more, continue here:
open_in_new Using Korean transportation apps (Naver Maps, Kakao Maps)