As you say, the drug itself is a plot device related to the 3d and showing off some nice effects. The thing is, from people who have seen it, they say that the 3d is actually very impressive when it's used for the slow mo scenes, and there are only a handful of them. I don't know about you, but I personally haven't seen an action film where a bullet passes through someone's skull and explodes their face in super slow motion and in your face. I'm looking forward to seeing more of that kind of stuff. I think the CGI blood is dead on. The blood extending over the border made it look like a nod to the comics rather than just doing it for the sake of 3d. And I think it looks HDR and bright like that because of the effect the 3d has when shooting film at anything over 60fps. The colours come out a little more toned down when viewing it in 3d. Peter Jackson had the same problem shooting The Hobbit. He had to colour the sets much brighter than what was normal.
Fair point about watching it in 3D; the blood will look darker, more real, and the effect should overall be more impressive, but it may mean the film will lose a lot in the transition to 2D, which is how I would watch it at home on Blu-Ray afterwards (resisting 3D television, cause I don't think it will take off.)
Interesting that you use the words "more evil". I recall watching documentaries about drug abuse, and usually any addictive drug is referred to as being evil
Ok, going to veer wildly off-topic here for a moment. Heroin is usually regarded as the most "evil" drug, but AFAIK, there was never much of a problem with it until it became illegal. During the late-40s/50s, there were a few thousand registered addicts in Britain, mostly guys who'd been treated with it during the war, and who came back hooked. They got scripts for it from the NHS, so they had a steady, clean supply of heroin, and had no problems with having to pay for it.
Then there was some sort of Senate enquiry in the US which concluded that the drug was highly dangerous, and that it should be banned; later, the results of that enquiry were debunked, and it's now thought that so long as you've got a clean supply of safe quantities, you can pretty much take heroin for the whole of your life and it wouldn't be that big a deal (unlike cocaine, which is supposed to be very harmful).
But a moral panic broke out, led by tabloid newspapers, decrying the fact that people were getting this stuff from their doctors. Heroin was banned, and a black market opened up for it, as criminals saw an opportunity to make some money off the addicts there. Once they copped just how effective this product was when you got people hooked on it, they started peddling it all over the place...and now there are many, many more addicts than there used to be, mostly in very deprived areas, who end up stealing to pay for their habit, and who are sold a product of questionable quality. More overdoses, more people shooting up with dirty needles, more heroin on sale that's been cut with whatever crap was convenient for the supplier to put in there. Thanks to prohibition, we went from a minor "problem" that would probably have died off with those WW2 vets, to the endemic one we've got now.
Anyhow, that's the anti-prohibition version of events, so make of it what you will.
Lena Heady's character might surprise you there and give you want you want. We all know woman can be more evil than men if they want, right? 
.
Of course she's evil...didn't you see that scar?!!! Still pretty hot, though.
