Not especially. I’ve been here for almost a year and never really had any issues. If you’re in Seoul or Busan, you have a very good chance of running into English speakers in your day-to-day.
The majority of street signs are in English and there’s a surprising amount of English words written in Hangul characters for businesses. So if you can learn the admittedly very simple Hangul alphabet, you won’t really have that many problems.
I absolutely adore living out here