Overall, as with most series, the interest wanes. The movie makers job was challenged by a much longer and intricate book this time. Anyone who has not read it or is familiar with all the characters (and even a few who are familiar with the characters but not the book) will get lost.
Others have commented on how Daniel Radcliffe does not inspire as Harry. The older actors are accomplished and inspiring.
Read the book. Skip the movie unless you are a die hard Potter fan and need to see it to be complete.
Fast moving film with diverse and interesting characters. The back story to the entire Star Trek lore; it is fun to see how bits from past films are alluded to (e.g., Scotty's giving the formula for extruded aluminum to an engineer in the Voyage Home is echoed by a future Spock giving him the formula for hide speed beaming in this film). This is but one of myriad references that are fun if you know them and don't get in your way if you don't. Go!!!
You will be disappointed. Three of us read the book first. We wondered why the inexplicable story changes, the loss of real terror and tension, extraneous characters, etc.
My teenage son, the visual thinker, loved the movie. He thought it the best of the year.
If you see it, absolutely see it in 3D. Each frame is colored and engineered to get maximum benefit from the effects. The stop action claymation yields every gamut of human (and animal) emotion.
OTOH, it is not the Coraline we had gone expecting to see the Gaiman story, apparently with his complete permission, has been gutted from its tight, simple tension.
By the way, I would recommend the movie to a friend who had not read the book.