I really liked the concept of this book, and it certainly delivered in terms of plot and structure. However, I kept finding myself thrown out of the story by random inaccuracies (such as the suggestion than the University of Cambridge offers a course in journalism - not only was this counter-intuitive, but also easily refuted by a very quick google search. There are numerous other similar mistakes, I think the author needed to do a little more fact checking, because really mistakes like that fall outside the remit of artistic license in my view). There were also a lot of Americanisms - so much so in fact, the book felt very much like it was set in small town America, the school particularly felt more like an American High School than a British comprehensive (and when a 17yo refers to the grade they achieved last year, they generally speaking they would be referring to an external exam result (either a GCSE or AS depending on which year group they are in), not a grade assigned by a teacher as happens in this book. Yes, I know I'm being nitpicky, but it's precisely these tiny details that made it impossible for me to find it remotely believable this was actually set in England at all.
Having said all that, I still would have rated this book with 4 stars, since it really was very enjoyable, and definitely did far more right than it did wrong. Except for the ending. It's one of my pet hates when authors end a book on a cliff hanger. Yes, i know it's part of a series, but to my mind each book in a serial should be entirely self contained, whilst still being part of a greater narrative. Take Katherine Kerr's Deverry series of an example of this being done right - or Stephen Donaldson's Thomas Covenant novels. They, and others, amply demonstrate that it is perfectly possible to give a reader closure at the end of a book whilst still leaving the reader wanting more. "Unspoken" does not provide any closure at all - it just leaves you hanging. And that is the reason I cannot give this book more than 3 stars. I may or may not read the sequel when it comes out. I want to know what happens, but at the same time I think I'd rather drop a series that doesn't close each book early on rather than later. As it is, I rather regret reading it in the first place. Which is a real shame, especially for what is otherwise such an imaginative and well told story.