There are lots of explosions and lots of macabre torture and darkness, but not a lot of plot advancement.
Part 1 is a long lead-in to the real story, which will presumably be in part 2. In Part 1, Harry and friends are chased all over England but there's not much tension in the movie. There are ridiculous pauses for weddings and dancing. Then, boom, we're back to the chase. No one is supposed to know where they're hiding, but then friends drop in out of the blue to help them out. (Why are elves slaves to witches when they're more powerful than their masters and mistresses?)
This doesn't make sense to someone who hasn't read the Potter books. Why are they after the horcruxes? Why don't they go after the deathly hallows instead, especially when they know what the hallows are but they don't know what the horcruxes are. And why aren't they working harder to find the horcruxes?