Let's start by saying that movies are rarely, if ever, "just like the book" and I get that. That's fine. Sometimes tweaks need to be made to make the movie more interesting, flow better, etc.
However, this movie as a book adaptation, was an absolute abomination to Potter fans. Several KEY events were bungled and my fiance and I left the theater saying "HUH?" As a fervent Potter reader, I was just stunned at one big scene that happened in the movie, which shouldn't have- some of the things they did are going to make problems for the 7th/8th movies.
The movie in and of itself was good- entertaining, funny, and it certainly didn't feel like its running length. I would see it again, but this time keeping in mind how inaccurate it was.