10/10
I was in Jeju with my wife for one week, we spent 3 nights at lotte city hotel and the rest here, at kai Hotel.
I can personally say that cleanliness was better (much better) in kai hotel than lotte, the rooms were really quiet and you will have a great sleep, the beach is only 2 minutes walking distance. The only problem was that the pool was closed :( but it was due weather problems.
I totally recommend this place !