DEH fanboys and girls, those who have or haven't yet seen the show, and those who don't care about musicals at all -- this book will satisfy them all. NO SPOILERS in this review, just a rundown of what I loved and didn't love.I'm a person who can't tolerate sloppy or clichéd prose, and YA literature is rife with it. This book is a happy exception. It's very well written and briskly plotted, with well-drawn characters I could easily picture in my own mind. The high-quality writing is the best part of the book, and in my opinion the most important part of any fiction book.Evan Hansen, the protagonist, is a bundle of neuroses, self-doubt, and self-loathing. For me, that got tiring after a bit, but I'm no longer a teenager. It might be that if I were 16 or 17 I'd feel a lot more empathy. Even so, Evan is likable enough to sympathize with, despite his many incredibly obvious blunders and history of awful decision-making. The ancillary characters are all vivid and well fleshed out, mostly representing high school "types" we all know well. I did feel that, in terms of character development, the adults are more sketched-out than thoroughly explored. I think this is true to the teenage mind, though, which conceives of adults as somewhat mysterious and capricious, and EH is a teen speaking in the first person, so it's appropriate.I haven't seen the show or heard the cast album, but after reading the book, I looked up the plot of the show. It appears that there is an important character added in this book that helps flesh out Connor's story. And Connor's story is left somewhat ambiguous; we're teased with a was-he-or-wasn't-he question that's never answered. That left me a little frustrated, because it felt a bit like the writer backed off a potentially controversial character trait by leaving it open. But that's a minor flaw. Overall, I was very surprised at how much I, a grown adult with no particular interest in YA fiction, enjoyed the writing, the characters, and the experience of reading the book.FOR PARENTS -- no spoilers of plot, but a couple notes on content, so don't read on if you don't want to know any more.There is a suicide in the book. It's not described and there's nothing graphic, but the aftermath reverberates throughout the story. So this may not be a great book for younger kids struggling with self-harm and depression. There is also a relentless emphasis on Evan's mental health struggles. If your child suffers from panic, social anxiety, or depression, I'd suggest you read the book yourself and decide whether your kid will feel empathy and relief at reading about others fighting the same battles, or whether the content might trigger more morbid feelings.