I think it's interesting that having Greedo shoot at all was a big contraversy with fans in the 1997 remakes. Is it just a matter of wanting to view Han as someone wary enough to fire first, or do we want him to fire first to more assuredly place him in the role of the scoundrel?
I don't want Han to be a hero or someone who in any way feels bound to operate within the confines of the law. I like him as a scoundrel and a rogue, but - I want Greedo to fire first. That way, we either accept Greedo as an incompetent bounty hunter or we see Han as lucky after the shot misses. When Han fires first I see it as his character jumping the gun. He's much more appealing after he's been shot or nearly shot (either way he must survive with luck) and then follows up by one shotting his enemy (also lucky?).
As for Greedo, I'd like to feel that he's competent and that this situation was a fluke. It would make Han more appealing if he got the better of someone who's good at what they do than someone who isn't. You don't brag about kicking someone when they're already down (if you want to remain a goodguy anyway). If Greedo is competent, the situation is more similar to Han's evasion of the star destroyers in a later scene. Insurmountable odds, but luck and skill see him through. It doesn't hurt that the SDs fired first as well.
Sorry, rambling.