Immanuel Kant is one of the greatest philosophers in history. As Peter Kreeft here notes, Kant is really two philosophers - a philosopher concerned with how we know things (epistemology) and a philosopher of right and wrong (ethics). If he had written only on either topic, he would still be the most important and influential of the modern philosophers. The combination of the two, though, makes for a formidable thinker, one it would take a figure such as Socrates to confront.
Kreeft's Socrates reflects what the historical philosopher would likely have made of Kant's ideas, while also recognizing the greatness, genius, and insightfulness of Kant. The result is a helpful, highly readable, even amusing book. Kant's philosopher of knowing truly is a "Copernican revolution in philosophy," as he himself dubbed it. His ethics intended to set out the rational grounds for morality. Did he achieve his goals? What would Socrates say about the matter?