I think if Notch's goal is to create a creepy mob (and lets be honest, creepers arent creepy, just explosive) then I dont think he could have done a better job. Yes, this is going to scare the crap out of people when they take their first sighting to the new mob, but it's one of those things you read about in stories, and fits well with the other mobs. Think about it, dead people comming to life as zombies, kinda the same with skeletons. Giant man eating spiders and now the scary shadown in the darkness little kids are scared of in the dark. Yea, its description is scary as heck, but I think it will test peoples ability to keep it together.