Libertarians tend to suck on environmental issues (hence this snark about the West Virginia chemical spill). On the other hand, they often go a great job discussing civil liberties issues, more so than any other identifiable political group.
I don't know that my opinion on those two issues seems terrible insightful. It seems banal or obvious to me, but it's apparently not allowed in the current ideological atmosphere to admit that reality has the kind of complexity that caused Robert Anton Wilson to talk about "model agnosticism." Apparently, you're supposed to stick to the idea that your side "rules" and everyone else's "sucks."
Sean Wilentz thinks libertarians suck, so he's become part of a long line of current writers attacking Glenn Greenwald for sounding too much like a libertarian. (I'm not going to link to his piece, but it's not hard to find.)
Will Wilkinson has a nice piece up on what's wrong with liberals and libertarians, focusing on the problem that many "liberals" seem to be abandoning their classical liberal roots as defenders of civil liberties. Here is a good passage excised from a slightly longer sentence:
Too many “liberals” are really conservative apologists for the status quo political order, just as too many “libertarians” are really conservative apologists for the status quo economic order.
Another bit I liked:
That anyone spurred to action against the illiberal security state by the democratic justificatory ethos of mundane liberalism has come to seem a little “libertarian,” and may even therefore confess some personal “libertarian” sympathies, suggests to me a problem with “liberalism” as it is embodied in actual political discourse and practice. It suggests that liberalism is effectively a corrupt form of statist institutional conservatism.