Wow this has got to be the most off-topic-going thread I've ever read. Oddly enough I found it rather amusing >_>, especially when KoRn_Dowwg666 advised about editing posts and strove to keep things on topic by with off topic posts. I must brag I know about the edit button AND about the PM (private messaging) :P
Now quick, as I still have a chance to post something on topic: HOH mode is exactly as the title says. It's all fun and games till you can't see those enemies with spinning shields (mission 14 I think). That sucked and I cheated my way through abusing Quick Silver. After you beat this mode you don't get an extra costume, nor an extra illustration or movie. All you get is two shiny jewel like circles (I think they are red and blue, but not sure at all) on your save game icon.....you know the one that keeps changing its color after each conquered difficulty.
PS: Damn! this question would have made a good riddle on the DMC3 riddles thread.