well in my opinion the darkest movie was PoA... but anyways i thought the movie was really good, actually my favorite of all of them, they did a great job getting the story out there and clear for non-readers...i think the whole cho snitching thing (instead of her friend) was good because it made us feel the same way about her as in the book (liked her, got mad at her, then ended up liking her again) that was helped by snape saying how she used the last bit of veritaserum on cho...so we knew she didnt "squeal" purposely