The movie starts off immediately following the events of Part 1. Voldemort retrieving the Elder Wand and the protagonist trio on the quest to find and destroy the remaining horcruxes (items where Voldemort hid pieces of his soul) to have a fighting chance against their enemy. There was always an impending sense of doom one can feel while watching, like someone or something was lurking in every corner out to make another famous character disappear from the series forever.
This is, after all, the second part of one story (and the last act of an entire series, at that). If there's anything to be gleaned about storytelling is that the boring part usually happens at the first act and it's all hyperkinetic pacing and climax at the end. At least when done properly. And David Yates and the screenplay by Steve Kloves handle the tale with just the right amount of precision and pathos to make even non-fans of the series appreciate what the characters are going through.
The cast members could practically do their respective roles in their sleep. But it was Alan Rickman's portrayal of Snape that got the most reactions from people. Especially so for those who had not read the books and got the surprise revelation about his role on the entire story. It was one of the most heart-rending vindication ever captured on film since Darth Vader
It's one of those things that make watching movies on the cinema worthwhile.