While it's safe to say that Kant is the most important philosopher of the modern world, the sine qua non for the understanding of the field, it is also fair to warn that the reading of his three critiques is not an easy task, even for those well-prepared by the study of his antecedents. Having basically invented a philosophical German, his prose is dry and abstract, his systematic method with its classical terminologies strained and artificial-sounding.
Alternatively, to get a taste of Kant at his readable best, one can try the texts based on his lecture notes, particularly the Anthropology. Its content alone, given the many asides and anecdotes, its very subject matter, is more generally interesting than his usual, more technical writing. It is as if one were reading a modern Herodotus.
There is a prevailing stereotype of Kant which maintains that he led a dull, sheltered life, governed by routine, in remote East Prussia. Based on the period of his fame when he was already an old man, it misrepresents the character of his whole life. In fact, as a struggling academic, given the character of German university economics of the time, Kant not only had to support himself by gambling (in billiards and cards, in both of which he apparently had some aptitude) and tutoring (which often took him beyond the confines of Konigsberg), but also by providing interesting courses which could sell by subscription to the public. The Anthropology was one such popular, and relatively lucrative, course of lectures.
Kant's sources for the contents of these lectures ranged beyond the published materials of the time. The son of a saddler himself, comfortably identified with his working class origins, he maintained comfortable relations with his kind and found, in the sailors at the port and in its neighboring bars (the young Kant being a notable tippler), much of interest about far off places and exotic peoples to report to his students. As an instance of some importance, note his report about apes and monkeys and his surmise of their origins, common with ours--almost a century before Darwin.