Long Ago and Not True Anyway has an excellent essay on the subject of What’s the Matter with Libertarianism? He's attacking "libertarianism" in its generic sense, rather than any particular denomination, but the arguments apply to all in any case. For me, there are two problems. The first is the deification of property rights and markets, rather than a recognition that they are simply a useful tool and therefore can be changed depending on the desired social end. The second is their monomaniacal fixation on the state as the sole limitation on liberty. This ignores the valuable role played by government in protecting the liberty of the individual from the depredations of the powerful, and reduces their vision of freedom to a cruel joke where people are considered to have "freedom of religion" even when some forms of worship result in private punishment no different from state oppression, "security of the person" where employers can demand sexual favours as a prerequisite for employment, and "freedom of movement" even when they are forbidden to step out of their house and onto the privately-owned sidewalk. This isn't freedom for all, it's freedom for the pike.
Then there's the hypocrisy of many libertarians who proclaim the sanctity of absolutist property rights while opposing even token restitution by the government towards the descendents of this country's original indigenous owners. But as LAANTA astutely observes, rather than being consistent,
What they’re really advocating is ‘start from now’ libertarianism which, funnily enough, almost-always finds its strongest advocates amongst those who are doing pretty well at present thank you very much.
Rather than being consistent and principled defenders of freedom for all, libertarians are simply engaged in what John Kenneth Galbraith called "one of man's oldest exercises in moral philosophy": the search for a superior moral justification for selfishness.