can't tell if your icon would pass the appstore review. But I like it. The zombie says it all. (arrrrgh! it hurts!)
Yeah, the zombie looks sick, but the knife might just add too much realism for our friends at Apple, and might even draw back sales.
I'd say try removing just the blood first. It doesn't really go with the rest of the image anyways. My 2 cents.
Nice icon! May want to think about making the smaller shapes bigger somehow? Like bigger patches of color? Not sure how it will look at 57x57.