Cheng Ji Si Han was a great Chinese hero of the Mongolian nationality.
I love this.
I see two sides to the issue.
1. It doesn't make sense to judge people from the past based on our current values.
2. We're so far removed from the death, violence and destruction he inflicted on a huge number of people that it's easy for us to ignore it.
I agree.
Genghis Khan's legacy is mixed, in my opinion. On the one hand, one cannot ignore all the killing and slaughtering he did. While such style of conquest was not too uncommon during his era, he was still pretty bloody even for his time, nonetheless.
On the other hand, as stated previously, he was pretty tolerant. He didn't care what religion, what beliefs, even what political faction you were on - even if you were his former enemy - so long as you proved yourself a worthy soldier or administrator or craftsman or what not. Unusually for his time, he preferred to reward people for their merit, not because of noble birth or some other kind of privilege. In that regard he was open-minded for his time.
He also was brilliant, as all good conquerors all, although personally I don't see him as a megalomaniac, but rather as a very calm and Machiavellian politician and soldier. His organizational and leadership skills had to be admired, and he definitely knew how to survive, judging from the fact that he rose from the nomadic equivalent of a orphan beggar-boy, through sheer intelligence and charisma, to become leader of all the nomadic tribes of Mongolia.
Still, of course, we can't forget that he killed craploads of people and that he's probably one of the most prolific guys who ever lived. The ultimate thing, though, I think, is that he the half-brained barbarian ape the media tends to portray him as. He definitely knew what he was doing, and, in my opinion, he wasn't some crazy raving lunatic - to me, he is one of the epitomes of the calculating, brilliant chessmaster.