The thing that's most fun to me about the original Iron Chef is the ingredient of the day. That, and the outrageous (to the American palate, anyway) recipes the chef come up with.
I haven't seen Iron Chef USA, but I can only imagine they'll be using more "mainstream" ingredients and the result will be pretty boring
Takeshi Kaga (as well as his wardrobe) is such a true original, he can't be replaced or translated!