I agree completely. That shot stayed with me for years. I can't even look at the box cover without feeling a little shudder. I know it's not your standard zombie movie, but I thought it really worked. I think the main difference between the Shockwaves zombies and traditional zombies is that the former kill for the sake of killing rather than eating. It made them much more rational, in a sense, although that's a strange word to apply to zombies.