I tried the Caramel KitKat for the first time last year and didn't really remember it, but recently came across more and had to buy. Upon (re)tasting, I came to a new conclusion: this is one fantastic KitKat.
The chocolate coating couldn't be any richer. It has a caramel colored swirl and although it didn't smack me in the face with caramel flavor, it was buttery and smooth. This may be as close to gourmet as possible for a KitKat. I really was sad to see this one go.
My friends at work also tried this KitKat and agreed that it was delicious.
KitKat Website (Japanese)