The great, glaring gap in just about all ethical systems of which I have knowledge, even when many of the particular values and virtues they advocate may be laudable, is the absence of a technology to assist people in getting there, an effective means for acquiring these values and virtues, a realistic path people can follow. That is the great missing step in most religions and philosophies.
You can tell people that it's a virtue to be rational, productive, or just, but, if they have not already arrived at that stage of awareness and development on their own, objectivism does not tell them how to get there. It does tell you you're rotten if you fail to get there.
Rand's failure to provide a "technology" for attaining Objectivist moral values is not her only failure in this regard. She provided very little in terms of achieving any of the things she regarded as desirable, whether it was rationality, persuasion, or laissez-faire capitalism. And on few occasions where she provided at least the outlines of a technology (as in aesthetics and "philosophical-detection"), what she actually gives us is deeply flawed. Hence the ironic spectacle of Rand followers who don't know how to be rational, Objectivists who don't know how to solve moral conflicts with other Objectivists, and the lack of a strong, vibrant Objectivist artistic movement.
1. No Method for Attaining Rationality. Rand waxed eloquent on the merits of "reason" and rationality, yet never really explained how to attain it --- at least not in sufficient detail. Instead, she left us quite a bit of moralizing rhetoric about forming concepts "properly," or "focusing" your minds, or integrating your thoughts into a logical whole. Some of her theories concerning knowledge, especially those revolving around definitions and concepts, are factually erroneous. The very term "conceptual knowledge," which she enjoyed bandying about, could be regarded as a contradicto en adjecto --- a contradiction of terms. Concepts are items of description, not units of knowledge, and are therefore neutral in terms of their truth or "validity." Rand's insistence on the importance of consciously formed articulable knowledge is badly misplaced. Actual knowledge (i.e., the cognitive processes that real human beings use in world of fact) work very different from how Rand imagined --- as cognitive scientists have known for decades.
Even worse than all this is the example Rand left to the world by her own conduct. When engaged in Q&A in front of an audience, she would not shrink from vicious personal attacks against anyone, even persons sympathetic with her philosophy of Objectivism, who asked a question she was uncomfortable answering. Rand was hypersensitive to anything she perceived as an attack, which made it very difficult for her to engage in rational discussion with people who disagreed with her.
2. No method for attaining virtue. In some sense, it isn't Rand's fault that she failed to provide an adequate technology for the Objectivist ethics. As it turns out, such a technology is not really feasible. Morality cannot be solely based on a consciously formed, articulable system of thought. There is absolutely no evidence that morality does or can work that way, and a quite a bit of evidence that the larger portion of what passes for ethics is the consequence of ingrained sentiments or instinct that is refined by experience, teaching, and narrative. (James Q. Wilson's The Moral Sense and Jonathan Haidt's The Righteous Mind provide the best introduction to the evidence supporting this view.)
3. No method of attaining political ideals. As Objectivism evolves, the political side of it gains increasing importance. Let's face it: many people are attracted to Objectivism chiefly for political reasons; and most of the hostility Objectivism inspires among its critics has its source in differences over political ideals. Yet despite the strong political orientation of Objectivism, its most prominent spokesmen, along with the movement in general, have virtually no influence over the public policy of any country in the world. As a political movement, Objectivism is a failure, and part of the reason for this is that Rand and her followers never provided any effective technology for persuasion. How could they? Since Objectivism has a seriously flawed view of human nature, it would unreasonable to expect Rand or any of her disciples to come up with an effective theory of persuasion. Quite the contrary, Rand and Peikoff seemed to believe that the course of history could be change by refuting the epistemology of Immanual Kant --- hardly an effective strategy for changing the world.
There's what people claim to believe, and then there's how people behave. In terms of behavior, Rand would often engage in triggering behavior. She would intentionally make statements that her ideological opponents regarded as palpably absurd and/or beyond the pale. While such iconoclasm might offer emotional gratification to Rand's admirers, it's disastrous as persuasion