I think my overall reactions are not particularly spoilery, for a film adapted from a well-known book, so, outside the cut:
In my opinion DH makes a better film than a book. I'm surprised how much of the book they kept, and perhaps that was a function of how convoluted the storyline is, that they didn't feel they could make major cuts and jumps and still keep even the concept alive. Part One felt a good deal like a chessboard being set up at midgame, piece here, piece there, so that come next film we can actually sit down and play with the board that's been set. They convinced me that one decent film could never have been made from that book without changing it radically (more so than even significant hack-and-slash). But they did show that they could make two decent films from it. Even without seeing the second film I'm going to assume that.
But, man, watching DH is to remind oneself of how interminable that book gets. I can't tell you how many times, despite the enjoyment of familiar characters, good acting, and a well-done book-to-script translation, I fell into the litany of
I miss Hogwarts, I miss Hogwarts, I miss Hogwarts. Hogwarts and the Harry Potter series aren't like jam and bread, they're like wheat and bread, with one part so integral the concept falls apart when it's gone. And camping is still camping no matter how many times you change the desktop picture.
( Spoilery specifics behind the cut. )