I am so happy that they finally released the Mad Hatter's route in English! I played the Japanese GREE version over the summer, and it has been my favorite story from the KBTBB series. Fortunately, I don't see any real differences between the stories - only a few translation things that I expected, a few minor background image changes, and some of the chapters were combined to create 13 instead of the original 15 (no content seems to be missing though).
One completely subjective observation is that I do feel like is that the character's personality came through more strongly (read: creepy) in the Japanese version because of the language choices.
Click "read more" to see walkthrough.