Now that you mention it, Draco used Peruvian Instant Darkness powder twice in “Half-Blood Prince.”
I saw the movie last night, and sadly, it showcased what I disliked most about the book. Throughout much of the book, HP does a lot of whining, complaining, feeling sorry for himself, yadda yadda. With good reason, sure, but it was annoying. That was captured pretty well on film.
The special effects in the battle between LV and Dumbledore were incredible, by far my favorite bit of the movie. My nine year old loved it, said it was his favorite of the movies yet. I rank it below PoA and GoF, personally.