The only reason I don't give this book 5 stars is that the writing sometimes lacks a coherent/intelligent edge. There's also PLENTY of editing and spelling errors in the Kindle edition. Neither is a dealbreaker, but they do "take me out of the story" if only for a brief period of time when it happens.
That said, I LOVE this series. The underground world is so perfectly visualized I find myself thinking about it quite often, even when I am not reading the books. I liked this one better than the first one (which had quite an epic *long* buildup before diving underground)..this one really gets moving. Since this is a 6 book series, I don't mind the extended periods spent in different locales. The authors spend lots of time going into great detail about everything, making it feel that much more immersive (or SUBmersive?)
I agree with most reviewers that these are not what I would consider typical "kids" books. There are some VERY tense moments, deaths, and themes of a dark nature that really tore at MY soul (and I am 44 years old). However, any mature kid can easily handle it - and the rewards are great. Think of it as a PG-13 movie...some kids can handle such movies better than others.
I am 100% committed to the series (halfway through book 3 and loving every minute of it). I am somewhat sad, as I will finish the current releases (up to book 5) in the next couple months and will have to wait a year for the final book. Gah!
I am so thankful that a friend mentioned this series to me in passing. It has it all - adventure, quirkiness, drama, mystery, death, brutality, suspense, plots within plots, and even tenderness. It really makes me feel inspired in ways I have not been in years (and I read all kinds of books, constantly). Reading it is a joy, and I find myself looking forward to each day's reading time with a bit of giddiness.
I like to think I have a spirit of adventure and discovery just like Will and his dad, and that this book is a secret world I have unearthed and cannot get enough of.