I think this movie is trying to do too many things at once. Character list got extended to the point I can't remember why I should care about who and what they are up to. It's like adding sub plots that seem strangely meaningless yet they are impacting the story in a way i do not get (I am not that verse in Harry Potter universe)

In the first movie the bi polarity of Good vs Evil worked better than in this. The morality has become "flexible" and the characters are making decisions that will probably have bigger effect in Part 3 than they are now.

Despite the negatives I list it is still a good addition to the trilogy and universe, but it is clearly the in between movie that is supposed to setup the final movie. It just does not work that well as a standalone part.