I realized last night after standing in line and listening to people talk about it before hand, that if you didn't read the book, I don't think you will understand the movie. Some kids were saying it was supposed to be like another Twilight.. please.. if it was, I wouldn't be going. It WAS true to the book (except 1 part with the pin, but I won't give it away.) The book was very graphic and had a lot of brutality in it, but the movie didn't showcase a lot of that. However, it didn't need to as you could understand what was going on and see their pain. But if you haven't read the book, it may be hard to understand. They put the most important character interactions and parts of the book in the plot. Awesome movie and great acting! Will not be disappointed :)
Put it this way, if you read the book, you will be very disappointed in the movie. They did not put enough of the memories in the movie, and they totally hacked the ending..Dumbledore never fell from the building, he was on the ground..not to mention the HUGE fight when Harry chases after Snape & Dracus through Hogwarts and the teachers and students were fighting the Deatheaters. The Burrow NEVER got burned either. I hate it when they change things from the book and leave important info out of the movie. I was very disappointed. The movie was still good and a couple really funny parts, but they just totally hacked the book and left out things that should not have been left out OR changed.