Don't start with Kant? Even the original German is supposedly incomprehensible.
Seriously though, Kant isn't a reasonable introduction to either "hard/great books" or philosophy. His philosophy is largely in response to the dichotomy between the empiricist and rationalist philosophers of the time. Or depending on who you ask, the empiricist/rationalist dichotomy that he created. Either way, it's largely a reference/response to Hume in particular, and also people like Berkeley, Locke, Descartes, Spinoza and Leibniz and the ideas they represented.