Kaiba is a good pal, he's a man of his word.
His only problem is his almost infinite anger occasioned by his past. But that's pretty much all, if he gets rid of such anger he'll become truly free.
I believe kazuki takahashi always said this. He said kaiba is not really an antagonist, the real adversary of yugioh was bakura whom is the embodiment of an ideology, just an abstract way of thinking, kids