I haven't seen NT still. like I said, it can be really cool. We can do the flaming skull and flaming wheels like Ghost Rider has with today's sfx. so it shouldn't be technical difficulties. Costuming isn't *too* difficult to do... leather pants and biker jacket with spikes... the bike may still suck though, and who knows if Nick can be trained to make it look like he knows how to use that chain.
But there's still story difficulties. Are they going to do a good story. GR isn't really a demon, he's a spirit of Vengeance. His power, beyond some extraordinary strength and resilience, is to look people in the eyes and they suddenly recognize the consequences of all their evil actions, reducing them to whimpering piles of human. Sometimes the guilt just burns them up. Hopefully the filmmakers haven't reduced that to demonic possession like Yahoo did. And hopefully they've got someone interesting for him to fight (the comics often did not).