Ok, here goes one of my lists. Things that weren't covered:
- Dumbledore's past: during the entire book the trio learns more about Dumbledore's past, his History with Grindelwald, what happened to his sister, his obsession with the hallows, etc. None of which was explained in the movies.
- King's Cross: When Harry is "killed" by Voldemort, he meets up with Dumbledore. Here's is where Dumbledore is supposed to explain to him all that occurred, why Dumbledore did what he did, his theories on Voldemort's obsession with power, why he thinks Harry will now be able to defeat him and, importantly, why Harry is in fact not dead and can return to the living. Instead, we vague riddles.
- Lupin & Tonk's son: At the end, when Harry finds the resurrection stone in the snitch Dumbledore gave him, Lupin appears to Harry and Harry says "But, Lupin, what about your son?" Yes, what about his son. A son, up until this point, had never been mentioned. I would think this would be confusing to those who did not read the books.
- Fred's Death: It appears the movies have a tendency to reduce the emotions that come with the deaths of some of HP's beloved characters and Fred Weasley is no exception. We never got to see how Fred dies. One minute he heads out with his twin to fight and the next he's lying in the Great Hall dead. I would have liked to see more.
- Neville's heroism: Yes, in the movie, Neville becomes a hero. But the transformation didn't seem as significant as it did in the books. For starters, Harry personally asks Neville to kill the snake. And 2nd, he does it in front of Voldemort after Voldemort burns the Sorting Hat on Neville's head not as the snake is chasing after Ron and Hermione.