If you read the books you may be a little disappointed. The beginning was much different from the book and a few things were left out at the end. It was still AMAZING, be prepared to laugh, scream and cry. This movie is intense but there are moments of comedy that will relieve the tension.
I swear i've never had a better experience in a movie theater, there were some parts where everyone was completely silent and other parts where we all erupted in applause. It was more than just a movie, everyone in that theater was bound together by the same thing.
Long story short; you won't even want to leave to go to the bathroom. (i held it for two and a half hours)