I agree with the other reviews by HPFan29 and Muggle13 that this book does a great job of blending together an introduction to some fairly weighty theological concepts with the fantastical world of Harry Potter.
The short version of this review: I'd definitely recommend the book.
The longer version: Exactly what you get out of it may depend a bit on the perspective you're entering from, whether you're a big HP fan with a passing interest in religion, or vice versa. (I'm assuming here that if you're hugely into both, you have already bought this book, and if you have no interest whatsoever in either, you would not have stumbled onto this page in the first place.)
The most obvious target audience would be students (or just curious individuals) who want to get an introduction to theological scholarship, but may be discouraged by the thought of having to pore over thick volumes full of literally millennia of dense philosophical arguments. For those folks, here's some good news: Even if you took out all the Harry Potter bits, this book would still be a great introduction to many of the core concepts of Christian theology (evil, sin, salvation, grace, etc.). The style is a bit more conversational and far easier to read than most textbooks, without being too cursory to be a useful academic reference.
The framework of examining these concepts in the context of the Harry Potter universe makes them even easier to digest; the typical structure is to spend a few pages introducing and discussing some theological concept, and then a few pages relating it to HP and his pals. This alternation of vegetables and dessert, as it were, is great for keeping you going if you're not too familiar with theology to start. Although "Yale" is in the title, and indeed that's where the course on which this book is based was originally taught, the good news is you don't have to be a Yale student to enjoy and learn from Reverend Tumminio's writing.
Academics and more experienced theologians will find lots here to like as well. Since just about everyone has read the Harry Potter books or seen the movies, the book's examples can provide some great ways to introduce theological concepts to students or acquaintances. English and literary majors may find this book of interest also, even if they don't specialize in theology; the sections on the Harry Potter world, in addition to illuminating the theology introduced in the rest of the book, also serve as a fairly substantial literary analysis of various the Christian themes present in Rowling's work.
All in all, the style is engaging, the pacing is good, and if you're interested in Harry Potter and/or theology enough to have found yourself to this page, I think you'll find "God and Harry Potter at Yale" an interesting and informative read.
