I've heard good and bad things about them, namely that the lifetime guarantee is not always worth the paper that it's written on. But these comments were on mtbr so I'm assuming that it is more to do with the American side of things.
i have read stuff like that, from what i read americans hate parts we like, they always have problems that Brits never seem to have. i have used Blackburns before and they are damn good pumps!