My Mayor's youngest son, Prometheus, has heterochromia. He has a gold right eye and a purple left eye. The reason is, when my mate and I were planning him out, we couldn't decide if he should have gold eyes (like his paternal great-grandma) or purple eyes (like his paternal grandma). So we gave him one of each.
I have two characters with heterochromia, one with full and one with partial :0
Personally, I think it's sorta lame when people give their characters really crazy heterochromia, like one pink eye and one black eye or something like that, but it's totally up to you since it's your character!!
It's not original, but nothing can really be 'original' anymore. Since it seems like some people use the same concepts for their OCs. I don't really mind it, I think it looks cool when an OC has it, but if any OC looks good, then I think it looks cool. I personally don't have an OC with heterochromia.
I mean, it's not original, but what really is anymore? The only thing I would say is don't spam it on all of your own characters, but that goes for pretty much all parts of character design...But they're your characters anyway, so it doesn't matter what I or anybody else thinks as long as you're happy with them.
Though sort of on subject; when blind people sometimes get those smokey, pale, 'dead' eyes, would that be heterochromia if it was in one eye, or would it just be 'being blind in one eye'?