This is quite simply the finest book written to date about a mainstream American comics creator. In the depth and breadth of its analysis, its lightly-worn erudition, its innovative ideas and its readability, it provides the tribute its subject (who, for those arriving late, is - among many other superlatives - the most influential artist ever to work in his medium) so obviously deserves.
The review by Greywolf is an excellent overview of what the book covers, so I won't waste your time reiterating his observations. However, his comment that the book isn't an analysis of Kirby's art is a bit wide of the mark. The very first chapter introduces the notion of Kirby's narrative art (which, to hideously over-simplify, develops the idea that every single mark Kirby made on a page advanced the narrative, though there's a lot more to it than that), while a later chapter on "the technological sublime" takes a fascinating look at Kirby's unique and under-valued (outside comics circles, anyway) science fiction art. One of Hatfield's many interesting ideas is that Kirby's influence now extends far beyond comics to any popular art form characterised by hyperbolic responses to imminent threat (i.e. pretty much everything on TV and at the movies these days). Nowadays, Kirby is like a vast underground river, irrigating not just comics but all media - which is why he's a hugely important cultural figure even if you've never heard of him, or even if you don't get his art. Hatfield's achievement is to link this convincingly not just to Kirby's character/series concepts, or his story-telling technique, but to every single aspect of his art.
This book isn't for everyone, though for everyone who digs Kirby, it's a must. Hatfield is an academic and while this is a lively, engaging read that's far from the standard image of an academic text, he takes his subject very seriously and isn't afraid to use concepts from the likes of Kant and C.S. Peirce to advance his arguments. In other words, if serious ideas explored in a serious manner aren't for you, and you don't like engaging with new concepts, well, there's plenty of "entertainment" choices for you elsewhere on Amazon. But for anyone who doesn't see any reason why great comics creators can't be analysed and discussed in the way that's routinely applied to creators in other fields, this is a must. I thought Kirby was a genius before I read this, but Hatfield's book made me realise there was far more to the King than I'd realised. It's a tremendous achievement and should set the standards for comics scholarship for decades to come.