The other reviewers have grabbed exactly what MacIntyre was getting at, if one combines their comments. It is certainly true that MacIntyre wishes to "skewer" the major moral philosophies of the modern day. This is absolutely necessary for his project. If he wishes to re-establish Aristotelian moral philosophy, he must first discredit those philosophies that have tried to destroy Aristotelianism. He does an excellent job, which is why After Virtue sparked so much debate. This book is a wonderful introduction to MacIntyre's thought, and is complemented by his Short History of Ethics (get the second edition). Any lover of Aristotle will be thrilled, and those who don't will be somewhat frightened and forced to re-think their positions.
In this work Alasdair MacIntyre argues that morality as we currently understand it has suffered a great disaster. As a result of the Enlightenment project's failed attempt to justify morality on its own terms, as MacIntyre argues, we are left with nothing more than shards of a once complete and coherent moral tradition. As a result the current state of morality is a form of emotivism, according to MacIntyre. MacIntyre's argument comes to a head when, in ch. 9, he claims that we must either go the way of Nietzsche's critique of morality or opt for a reworked version of Aristotle's ethics in which our moral claims can be justified.
This work is, in part, resoponsible for the renewed interest in virtue ethics among contemoporary moral philosophers. Regardless of whether one ultimately affirms or denies MacIntyre's conclusions this work is necessary reading for anyone who wishes to keep informed of current debates in moral philosophy.
Along these same lines I would recommend MacIntyre's other works which include Three Rival Versions and Whose Justice? Which Rationality? as well as Bernard Williams' Ethics and the Limits of Philosophy, and John Rawls' Political Liberalism.