I write this review in the assumption that you have read the book, and may or may not have seen the film, but don't mind hearing my thoughts on it. Then again, would you be reading this review if you wanted everything about the film to be a complete surprise?
I went to see Harry Potter and the Half-Blood Prince yesterday, and, being a Wednesday, the queue was very nearly out of the door, as probably most of the cinema-goers, like myself, had Orange mobile phones and were taking advantage of the two-for-one offer.
So far, I've considered the Harry Potter films to be either faithful adaptations of the books, or great films in their own right. I considered The Prisoner of Azkaban to be the most impressive visually, but that it felt very different from the book. I was a bit disappointed with Lupin (I don't know if it was his stupid little moustache or plummy voice, or his refusal to say the word, "werewolf.") And talking of werewolves, I was not very impressed with his transformation - he looked as though he got stuck half-way! I was under the impression that a werewolf looked like a wolf, not a wolf-human hybrid. A few things were cut that I thought should have been revealed - such as the identities of Wormtail, Moony, Padfoot and Prongs, that Harry knew by Order of the Phoenix.
The first two movies were very good adaptations, which brought Harry's world to life, with a real sense of atmosphere - but the script was lifted straight off the page with few additions. I think a film adaptation of a book should have enough differences to make it worthwhile to read the book and watch the film, without feeling you are having the same experience twice over, but still keep the overall story, characters, and spirit true.
The Goblet of Fire and The Order of the Phoenix, I thought, were better overall: more adventurous with the script but without sacrificing the story, but not quite as impressive to look at as Azkaban, to my mind.
Harry Potter and the Half-Blood Prince is the most "epic" of the films. It has a feeling of decided eeriness. This is no longer the fun, Enid Blytonesque world of Hogwarts where although Harry et al get into danger, you know they will be all right. The destruction of the Millenium Bridge, a real landmark, makes you think it's not just the fictional places such as Hogwarts that are in danger but the Muggle world too. In the book, despite the reports of Dementors roaming at large and Death Eater attacks, and Harry's fears about Malfoy being a Death Eater, the story felt pretty safe, as a lot of it is taken up with teenage romantic angst and Harry learning about Voldemort from the safety of Dumbledore's office.
I became more aware of the music in this film that I had been in the others. The score is more dramatic, adding to the unsettling atmosphere, with some choral parts that remind me more of the later installments of The Lord of the Rings and Pirates of the Caribbean.
The script, again, follows the story, with a few minor detours before coming back to the original material, not necessarily using the same scenes or dialogue as Rowling wrote, but serving the same purpose. There was one moment, about halfway through, however, when I did not know quite what was happening. They introduced an incident - Death Eaters attacking The Burrow - that was not in the novel. One thing I admire about Rowling's storytelling is the fact that everything happens for a reason, all the events are linked together. The Death Eater attack seemed to serve no purpose in the story other than reminding the audience of the ever-present danger. It leads nowhere - how can it, without derailing Rowling's entire plot? - and it doesn't ring true, as the Death Eaters could quite easily have killed off Harry and any of the Order, but didn't even seem to try, just taunting them and setting the Burrow alight. Then again, I spent the first minutes of that scene thinking, "what's happening here?" and not really watching as closely as usual.
I realised suddenly, that "Little Whinging, Surrey," must be pretty much where I used to live when I was in my second and third years at university, because when Dumbledore comes to take Harry away, he is hanging about Surbiton station. It was labelled as Surbiton, but it was Harry's nearest train station, so he must have lived in a village on the outskirts. Little Whinging can't have been another name for Berrylands, Tolworth or Hook, as they have their own train stations, as does Thames Ditton - but it could quite logically be another name for Long Ditton, my old home.
There was a sense of danger throughout the film that I didn't get from the book until the "Cave" chapter near the end. In the book, despite the reports of Dementors roaming at large and Death Eater attacks, and Harry's fears about Malfoy being a Death Eater, the story felt pretty safe, as a lot of it is taken up with teenage romantic angst and Harry learning about Voldemort from the safety of Dumbledore's office.
Harry enters the cave a boy and leaves a man. The Half-Blood Prince is also the coming-of-age story of his nemesis, Draco Malfoy. Before, just an arrogant, cowardly bully, Malfoy almost becomes a full-blown baddy. Yet, it is clear that he is out of his depth, charged with the task of a hardened villain, but still just a frightened boy, for all his bluster. We are shown his progress as he works on the vanishing cabinet, his tireless efforts, his despair, his emotional battles - because although Malfoy is a nasty piece of work, he is not a Death Eater at heart. Tom Felton did a wonderful job of portraying the tortured youth who is in too deep - although he is looking far older than the sixteen-year-old he is supposed to be. (In actual fact he's my sister's age.)
Recognition also must go to Alan Rickman as Severus Snape. There was something chilling about his performance in this film, as in the book. He is a double agent, spying both for Dumbledore and Voldemort - and gives no clue either way as to where his true loyalties lie. Just as in the book, Rowling gives evidence in favour of him being a good guy and a bad guy, and no definitive proof (until, it seems, the end,) Rickman keeps his face a mask, expressing nothing - and yet you can really feel his torment, at having to live so many lies - that no one can know what he is thinking or doing.
I wasn't disappointed by the final scene - on the Astronomy tower - but it wasn't how I had pictured it. I have a clear image from the book, of Snape sweeping up the stairs, through the crowd of Death Eaters, roughly pushing them aside and standing to face Dumbledore, before pointing his wand and saying the fatal words. In the film, Harry stood below the tower, and Snape saw him and shushed him before creeping up. And Dumbledore's "Severus, please" sounded too calm - it seemed too obvious what he meant, when it should seem like he was begging for mercy. Then again, reading the book, I knew what he really begging before I realised the more obvious - and wrong - meaning. I was disappointed that after Harry called Snape a coward, we didn't see Snape's mask slip for a moment and hear him cry "DON'T - CALL - ME - COWARD!" I found that a very powerful line - Snape has just done the hardest thing of his life - but I can't imagine Rickman's Snape losing his cool like that. It doesn't suit his voice.
On the subject of voices, Lupin sounded more like I thought he should this time - although he still had the posh accent, his voice sounded rougher around the edges. I was sorry not to get the bits of back story - his work for the Order among werewolves, having been bitten as a child by Fenrir Greyback, his budding and reluctant romance with Tonks. But I recognised that was not necessary to the plot, and what we did see of him was powerful. He only had a couple of lines - getting angry with Harry for being "blinded by hatred" of Snape, but we were shown that he is still finding it very difficult being a werewolf. I was also pleased to hear Tonks call him "sweetheart" at one point.
Harry Potter and the Half-Blood Prince is perhaps the one I have the fondest memories of reading the first time around, and the film adaptation did very well at replicating the experience for me. Yes, there are a lot of minor differences, and it certainly will not replace the book for me, but I shall certainly go to see it again. Already I am looking forward to the DVD.