The British Board of Film Classification has rejected Manhunt 2 for its "unremitting bleakness" and "casual sadism." This means you won't be able to buy it legally in the UK, unless Rockstar resubmits a changed version of the game.
Here's the BBFC's announcement in full. It makes for interesting reading...
%26ldquo;Rejecting a work is a very serious action and one which we do not take lightly. Where possible we try to consider cuts or, in the case of games, modifications which remove the material which contravenes the Board%26rsquo;s published Guidelines. In the case of Manhunt 2 this has not been possible.
"Manhunt 2 is distinguishable from recent high-end videogames by its unremitting bleakness and callousness of tone in an overall game context which constantly encourages visceral killing with exceptionally little alleviation or distancing. There is sustained and cumulative casual sadism in the way in which these killings are committed, and encouraged, in the game."