Kingsport Horror, the second "big box" expansion for Arkham Horror, is a must purchase for fans of the board game. It adds new elements to pretty much every aspect of the base set: new investigators, new gates, new items, new encounters, new monsters, and (last but not least) the Epic Battle variation which adds a significant and challenging twist to your last stand against the Ancient One. But this expansion is more than just markers and mechanics: it also introduces characters and locations from a wide variety of Lovecraft's writings into the game, making his world larger - and more frightening - whether you play with all of Kingsport or just mix a few extra cards into the standard game.
4 1/2 stars, rounded down because I find the rift progress mechanic unwieldy (but still fun).