Short Version: Harry Potter and the Half-Blood Prince might be the best Harry Potter film yet.
If you really care about Harry Potter, Ron & Ginny Weasley and Hermione Granger as living, breathing characters then you're going to love Harry Potter and the Half-Blood Prince.
Disclosure: I've only ever read the first book and while I've thought the previous films were "OK," I've never been a huge fan of the series. This latest film was directed by David Yates, the same fellow who directed the previous film Harry Potter and the Order of the Phoenix - and for perspective, I don't even remember was that one was about.
Having said that, I believe this latest installment is arguably the best Harry Potter film that's been released so far.
This is the sixth year Harry and Co. will be attending Hogwarts and they've all come a long way from the kids we saw back in the first film. They're certified young adults now and it's a pleasure seeing them on the screen with much more depth and complexity in themselves and their relationships with each other. As a matter of fact those relationships are what make this movie shine.
Harry (Daniel Radcliffe, of course) finds a book on potions that has copious handwritten notes by "The Half-Blood Prince." Whoever this person was, he was brilliant and creating potions - subtly modifying the recipes in the book to make them all work perfectly, was one of his skills. Harry's newfound "skill" at potion-making draws the attention of newly re-recruited professor Horace Slughorn. The professor is played by Jim Broadbent, who gives an excellent and surprisingly nuanced performance considering the (apparently) comedic nature of the role.
It turns out there is a very important reason that Slughorn was enticed to come back to Hogwarts, and professor Dumbledore (Michael Gambon) enlists Harry to pry some hidden information from the returning professor. Professor Snape (Alan Rickman, whose brief time on-screen is reason enough to go watch this movie with his mesmerizing screen presence) is involved, and his true(?) purpose becomes clear by the end of the film.
Much of the film is dedicated to the interrelationships between Harry, Ron, Hermione and Ginny. There is much teenage romantic angst - something that would normally trigger my teen-soap-opera-eyeball-roll reaction, but it's handled so sweetly and deftly here that it's a pleasure to watch and really draws you in to what they're all going through. Emma Watson, Bonnie Wright and Rupert Grint all do a fine job.
In combination with that, the gorgeous, muted cinematography and fantastic visual effects (not just in execution but style as well) is just icing on the cake.
Is this film perfect? No. One complaint I've heard from others is that over the course of 2 1/2 hours nothing much happens to move the story forward - and that the ending of the film (which has a definite Empire Strikes Back vibe) could have been a bit more effective. However these points detract very little from the overall enjoyment of what I think is the best summer blockbuster film of 2009.
Harry Potter and the Half-Blood Prince is rated PG and provides a few scenes that might be a bit intense for the littler ones, and there's one jump scene that will probably get them - but nothing too over the top. And frankly it was a pleasure to watch a movie aimed at the same age group as Transformers 2 without a single word of foul language to be heard nor anything that'll make a parent squirm while watching it with a child.
This may be the first Harry Potter film that I end up watching more than once.