I read _Atlas Shrugged_ without any preconceptions (I didn't know who Ayn Rand was, and Libertarianism wasn't nearly as trendy back then). I was taken in by the story of how everything fell apart, but was completely turned off by her solution—creating a "utopia" is quite easy when you only allow in a select few and have unlimited free energy. It struck me as the Libertarian equivalent of _The Jungle_: tell a compelling narrative of how society is (or can be) broken, and then destroy the credibility you've built by presenting your ideological vision while completely ignoring potential pitfalls.
This is exactly what I love about that book. To many it's a bible of libertarianism. To many it's everything that's bad about it. Either way I find it definitely encourages debate and thinking - much more than her other works.