Some have been disappointed by it, some consider it the best movie of the series. I liked it a great deal, and I don't honestly know if I HAVE a favorite movie of the series. I like them all, though I admit I am not a rabid fan, just a fan. I think for me its really a question of admiration for Rowling's storycraft. I've been told that her writing itself is not the most skillful, and I will readily conceed that her building blocks have been used to death in other medium a million times before.
But the skill with which Rowling uses those blocks is utterly amazing. Its like macaroni art put together by Michangelo. The individual components are simply not that impressive, but the artistry of the work itself is undeniable. The plots are pretty transparent despite a valiant effort to make them novel and interesting, but at the same time Rowling does so with a freshness and daring that makes them truly wonderous. Moreover, Rowlings characters are truly human. They behave in human ways and incorporate a larger spectrum of humanity than is to be found in most literature period, much less the YA genre.
Rowling trusts her readers with darkness. She never hides behind the fact that there are dark things out there, and her dark figures do not act like stereotypes (or rather JUST like stereotypes) but like the real thing. More important, her books are an enjoyable read. The movie is no less so.