As a huge fan of the books, it's always a dicey move when seeing a movie adaptation of a book. You are always afraid that the only similarity between the book and the movie will be the book title and the character names.
Nobody could compress HPatHBP into a 2.5h movie, but I felt they did a great job of capturing and portraying the critical plot points, while revealing the relationship evolution of the students.
We will probably go see it again (possibly in iMAX), so consider this a glowing review.
I was a fan through the whole seasons of the show, and the movie didn't disappoint. I loved it, as did my wife. If you enjoyed the show, you will LOVE the movie.