I agree that Neville's role in the prophecy and the last battle was greatly understated which I thought a shame.
A little thing, but in the book Snape's memories are pouring out of his every facial orifice so it was odd for them to change that to a couple of tears.
The scene with Snape talking to the strangely small collective school then Harry leaping out was really odd and didn't seem to add anything to the cinematic story at all. It seemed to be there purposely to remind us to hate him and didn't fit with his role at all.
Neville mentioning the Carrows must've been leading to a scene left on the cutting room floor as without having read the book their reference was meaningless.
DH hasn't read it since the book came out and ge was flummoxed over Malfoy who's good/badness wasn't clarified at all and his role in the film seemed, at best, limited.
I also didn't like how the connection with Voldemort was changed with him feeling the death of the horcruxes rather than Harry seeing him looking for them. It seemed a bit lacking that way.
I also wasn't a fan of how the final battle panned out with Harry and Voldemort alone rather than in the Hall though the flying bit was very cool.
On the good side was how it was visually. I particularly liked the stone knights, they were probably some of the best special effects I've seen in a long time! The protective spells around the castle were fab too and the dragon from Gringotts.
They were so funny as grown ups!