Id visited Jeju Island about 4 years ago 
and it was absolutely beautiful 
I ve been some famous islands 
such as Guam, Hawaii, Canary Is, and Bermuda 
each of these are pretty attractive.. 
but that's all 
theres nothing special that represents its own 
however Jeju has its own personality and characteristic 
that attracts people's mind 
it isn't seem like some luxury islands like hawaii 
that has big casinos and hotels 
but its quite and relax place... 
I wish i could visit Jeju island again 
if I have a chance