Your experience with thesis-based master’s degree will depend on the academic advisor, so, choose carefully. Some of the professors are chill, some of them are toxic, and some might actually not work on your research field anymore. If you plan to enroll for the coursework, then, it’s nothing special (at most parts). Since the university is research-focused, most of courses I took were rather easy and, at parts, useless (this one is highly subjective). One definite advantage of KAIST might be it’s reputation. It has a solid reputation when it comes to South Korea. If you plan to work in this country, then, KAIST is one of the places you want to study at. I am not sure about its fame across the world. I think it’s not that high.