I personally liked the book.
The author apparently has some kind of semi-Christian background from what I can tell. Her theology is definitely suspect - probably some kind of Universalist - but it didn't ruin the book, thankfully. The greatest theological oversight was in not defining why the Light is stronger than the Dark - as Christians we know the answer to that, but this books leaves that question sadly unanswered. (Another annoyance is a scene in a church that rather than defining a church as "Light" territory, defines it as 'safe, neutral' territory.)
There is definite strong C.S. Lewis and J.R.R. Tolkien influence, particularly Lewis in the outside-time descriptions (there is a chapter in Mere Christianity that is about his theories about what it is like to be outside Time) and the something, something with a strange name that I can't remember... (that aching, longing feeling that Will has, particularly when a certain strain of music is played) he also called it "northerness".
And, as a side note, I loved the character of Merriman. He's going to be added to my list of 'favorite fantasy mentor characters'. Very three-dimensional.
I did get lost in the jumping around in time, particularly concerning Hawkins/the Walker...
The book was better in some ways than the movie. In some ways, the movie was better. It's not an overly well written film. Their Checkov's (sp?) guns were not done very well, and Will is a very inactive MC; doesn't use his powers very often at all, and must be forced to do anything up until the end. But that being said, there were things in the book that relied on the narrator, which really worked better in the film. And, some of the additions and mini-plotlines and tensions between the siblings worked very well.
I am disappointed in the film, though, that it did not capture the beauty in this book, making it more of an action/adventure film with tons of flashing lights, fast cuts, and some really creepy birds.
