David Yates skipped a few parts, but put in a few additions of his own that made the movie loveable. It was very informative for the movie-goer that hasn't read the books, yet very entertaining for the book-reader who may be apprehensive or skeptical of the movie.
Overall, I say either way... go see it. The movie does the characters justice, they're all growing up and it shows expertly on screen.
Plus there's enough humor and awe to keep fans of all types very much engaged and guessing until the very end!