The prologue is gripping, the first chapter drags a bit, but the rest of the story is incredible. Powers manages to weave together the history of piracy, the age of sail, new world vodoun, and old world magic into an amazing tale which has served as the basis for both the Pirates of the Caribbean franchise and the Monkey Island computer game series -- indeed, re-reading it now as an adult I realize that many elements from the first half of the book were used as a jumping off point for the television series "LOST"! Ponce de Leon, Blackbeard and Baron Samedi all make appearances and it contains a fascinating explanation for why magic ceased to work in the Old World and seemed to flourish in the New World for centuries after the "discovery" of those lands.
Be forewarned, the structure of the narrative is non-traditional, flowing far more like real life than your standard fictional story. If you enjoy that, then this book will be delightful; if you don't, then you might want to search for something else a little more common.