It's important to separate objections to utilitarianism from the obvious fact that it can very be hard to correctly apply the utilitarian calculus. It's partly because of this difficulty that most classical utilitarians thought that people should generally follow commonsense morality and not try to directly apply the utilitarian calculus (which then led to the charge of paternalism and teaching one morality to the masses and another to a supposed elite).
But there are also people who just oppose utilitarianism, like G.E.M. Anscombe. For instance, in https://integrityproject.org/wp-content/uploads/2015/07/mr_t..., she seems to grant that dropping the nuclear bombs on Japan was probably good from a utilitarian perspective (because it saved lives overall) and also to grant that bombing campaigns that necessarily entail massive civilian deaths (including, apparently, area bombing German cities) are morally permissible but still to argue that dropping the nuclear bombs was impermissible because it constituted murder ("intentionally" killing the innocent). But this kind of distinction, which I think is what actual anti-utilitarianism must come to, is hard to even consistently maintain, and I suppose many HN readers would find the effort quixotic.
But there are also people who just oppose utilitarianism, like G.E.M. Anscombe. For instance, in https://integrityproject.org/wp-content/uploads/2015/07/mr_t..., she seems to grant that dropping the nuclear bombs on Japan was probably good from a utilitarian perspective (because it saved lives overall) and also to grant that bombing campaigns that necessarily entail massive civilian deaths (including, apparently, area bombing German cities) are morally permissible but still to argue that dropping the nuclear bombs was impermissible because it constituted murder ("intentionally" killing the innocent). But this kind of distinction, which I think is what actual anti-utilitarianism must come to, is hard to even consistently maintain, and I suppose many HN readers would find the effort quixotic.