The BBFC are to be congratulated for making a sober decision. They make it very clear in their statement that this decision was not taken because of the media-fuelled furore around the original game or the recent political pressure directed against games in general. Their concern was not just that children might get hold of it (if you're allowing your kids to play 18-rated games like the original Manhunt, you are in no position to blame the publisher for your poor parenting decisions) but that it would involve risks to adults AND minors. I am no fan of censorship and find the recent tendency of the press to blame games for murders tiresome, but it's good to see that the BBFC genuinely understands the medium they are regulating and are able to cogently explain their judgements.
I played the original 18-rated Manhunt, which was no more or less amoral than the many, many 18-rated movies of similar theme: it was a mediocre game that sold well purely for its notoriety. Had the press not made such a fuss the first time around and boosted the sales figures I daresay a sequel would not have been viable, let alone made.
A lot of adult gamers (who generally don't like being told what they can and cannot play) will be up in arms about this - although some will simply import the game from the US - but if the industry wants videogames to be taken seriously and respected as an entertainment medium it needs to show that it can obey the same rules as movies, TV and music. Game players have grown up, and it is only right that the industry does likewise.
I reacted the same way as most of Slashdot did initially, with indignance that I - an adult - was being prevented from playing a game to protect the widdle kiddies... but reading the full statement from the BBFC persuaded me that this is not their reasoning at all. I imagine they would ban a rape simulation game too if such a thing were released for the PS3, and I can't honestly say that's wrong. Free speech is a right, yes, but not a licence to piss off everybody just because you can. Pity there isn't some independent body doing the same job for journalism.
Besides, they banned two games in ten years. Hardly the Nanny State, is it?