I enjoyed this book - perhaps not as much as other reviewers! - but it was an exciting page-turner and just as good, if not better, than many in a similar genre. Other reviewers are right that the characters are very real and well-rounded. So what stopped me giving four or five stars? Well, at points I felt the story went 'off the boil', for example when Marcy had to stop and help her mum get dinner ready - it seemed like the urgency was lost - I kept thinking about Big up there in the woods but Marcy seemed to have forgotten all about him!
The other minor grumble where the story could have been improved was the pervading acceptance on the part of all the characters of the self-evident existence of bigfoots (bigfeet?!). Now, I retain an open mind about these things but I think the story would have been strengthened if there was a character who was similarly sceptical (along with the orthodox view), which would have given me a way in to suspend this scepticism.
But overall, a good read with only a very few typos (unfortunately all too present in so many e-books).