Well, I'm no Randian, I can tell you that much. I have made an effort to try and understand her works, but it has been a challenge. I have attempted to sit down and read
Atlas Shrugged a few times, and
Fountainhead once. As literary works, I consider them terrible.
TVTropes has a good breakdown of the literary elements that are present in the work.
Part of my criticism of Objectivism stems from the books, and my criticism of mainstream American Libertarianism largely stems from my criticism of Objectivism. I don't fully understand all the foreign versions of libertarianism, and I've heard that libertarianism was more associated with socialism in some countries, which sounds like the complete inversion of the philosophy.
The short story: I find the supermen amongst sheeple motif, the whiter-than-white superperfect good guys against the sniveling, evil cartoonish villains off-putting. It's over-done, the characters are monochromatic, and virtually interchangeable. Objectivism seems to be an utter misnomer to me--it's entirely based on the self-interest of great men, which seems to be by definition subjective. Beyond the traditional moral concerns of open endorsing greed and exploitation, it does not seem to be entirely consistent with the plot of the book or even with the free-market capitalism Objectivists pursue--after all, violating basic property rights, theft, or violence itself could be the easiest way to achieve your 'rational' self-interest to horde wealth.
Modern Am-Libertarianism is just dominated by these types. This has already been a long post so I'll avoid writing too much more here. It seems to have shifted to a political philosophy obsessed with the protection of wealth and the ability to make it at any cost to the rest of society, because after all 'Objectivists' don't care what happens to the rest of us. It's not in their self-interest.