What's so bad about the philosophy of Immanuel Kant?

In academic philosophy, Kant is often regarded as the culmination of the Enlightenment. According to this standard views, Kant sought to save reason from skeptics such as Hume, he aimed to ground ethics in reason, and he defended human autonomy and liberty. In contrast, Ayn Rand famously regarded Kant as "the most evil man in mankind’s history." She rejected his metaphysics, epistemology, and ethics, saying that "the philosophy of Kant is a systematic rationalization of every major psychological vice." Who is right here? What's right or wrong with his philosophy? Are Ayn Rand's criticisms justified?