I've noticed that most of the parts that I wanted the film to keep all had Ron in them:
Ron and his constant whispering of magical words to the radio and finally getting the right password. I just find this part so happy and funny in the midst of so much destruction and insecurity.
Harry and Ron talking when he comes back and he is explaining about the deluminator saying that Dumbledore must have always known he would have walked out, but then Harry turning around and saying 'no, he must have always known he would want to come back.' - such a heartwarming, guy love moment.
Ron's birthday present to Harry: 'How to charm witches' and then trying it out on Hermione.
Hermione getting really angry at Ron when he comes back and Harry casting the 'protago' spell between them.
Luna's room with all the painting of Harry, Ron, Neville and Hermione, all connected with ribbons spelling out 'friends'
Xenophilius Lovegood's crumplehornsnack exploding.
Ron going insane in the cellar of Malfoy Manor whilst Hermione is upstairs
The invisibility cloak in Godric's Hollow
Despite this, I loved the film and I suppose those bits are just things that stuck in my mind from the book, and I suppose everyone has small, almost insignificant elements from the book that they love contrary to their importance. I am actually so happy that most of the parts that I loved from the book stayed.