Disclaimer: I haven't read any of the books, but have seen all the movies, and, up to this one, I think each one has been better than the last.
My main complaint is that there wasn't really a story arc. I find it difficult to even identify the climax. Killing off a major character, especially the way it was shown, a climax does not make. I remember feeling, OK, now this is when the good stuff starts, and then the movie ended.
There was way too much teen-angst filler. This movie should have been cut in half and prepended to the next one (which I hear is half of book 7).
On the plus side, the supporting actors are excellent, as usual for the series.