I didn't read the book, but the friend I watched with did. Yet we both had the same reaction overall. The first third was excellent, very involving, interesting, with shades of Stand By Me and Alien, but the last 90 minutes became less original, and by the end, I no longer cared much about the story or the characters. Having not read the book, I found the story extremely complicated, with so many characters, I kind of lost interest. It needed more of the scenes with the kids, so their characters' continuity would resonate better. My friend was also rather disappointed after liking the first half, so it probably isn't vital to have read the book. Left me feeling dissatisfied.