At the outset it seems a perverse text, undoing what other texts in the Tanach tell us: that there is a God in heaven (who sometimes reveals Himself on earth), and that He makes sure that everything turns out for the good, especially for His chosen people the Jews, even if they have to wait around a bit. In the strange and alien story of the Megilla, God is noticeable by His absence.
Moreover, the Jews do not appear to observe halacha, in fact they violate some of its most sacred traditions. Esther, for example, marries an unstable, goyische king at the behest of her cousin Mordechai, who may be married to her according to some of our most distinguished rabbis, including Rashi. Similarly, when the peace-loving, if passive, Jews of the time get the opportunity, they merrily slaughter 75,000 and more of their fellow citizens. What is going on here? Is this why we celebrate Purim, for the wrong reasons?