It's difficult to discuss Manhunt 2 effectively without some sense that there's equal footing among everyone in the conversation.
Everybody can weigh in on how the age-rating system should work for this type of game, even if they don't know anything about the specific action except that it's extremely violent. It's fair to discuss issues like potential censorship, or the marketing of mature materials to minors, in general terms. Some new twist in violence will always come along, but that possibility can be accounted for in debating how to have the best system of oversight - or having no oversight, if that's your conviction.
On the other hand, there was continued howling today about the particular ugliness of Manhunt 2 from people who apparently haven't seen any significant amount (or maybe any portion at all) of the retail version that's being released this week. They may not be wrong - at least not ultimately - but that's not the way to conduct an important debate. Everyone plunging into that argument should be reasonably familiar with the actual game play.