This movie was complete shit. Nothing happened, it was emo, and we never got to know any of the kids siblings or parents well enough to tell which if any of the monsters were supposed to be stand-ins for whom.
I never read the book and I picked out the parallels between the characters just fine. Granted, I also made sure to enjoy the movie and not to sit there the whole time making a "HRMPH!" sound with my arms folded like you apparently did.