If not for anything else, the “Harry Potter” flicks that started eight years ago will be remembered as documenting the physical changes that occur in its lead stars. They started as kids. Now, Emma Watson at 18 in “Harry Potter and the Half-Blood Prince” has become even more appealing and attractive as the spunky Hermione. Rupert Grint as Ron still looks a bit older than the rest of the young cast and provides comic relief. The biggest change is in Tom Felton as Draco Malfoy, who used to be so cute as blonde boy. He’s now the tallest among them and Daniel Radcliffe, now 20 years old, looks so short beside him even if his acting has become more polished. Bonny Wright has also become quite a charmer as Ron’s sister, Ginny.

The sixth installment in the series is the first movie where you already know how the whole story would end since “The Deathly Hallows” has already come out and is now being filmed in two separate parts to be shown in 2010 and 2011. But this will not hamper the movie from being another blockbuster just like the preceding five films. The massive “Half-Blood Prince” novel is surely difficult to adapt on screen and screenwriter Steve Kloves must have agonized on what should be included and what we should be taken out in the film version. Now that the students are grown ups, they are made to deal with more serious issues involving death and loss, making it less whimsical than the past films. Fans of the book who want overly faithful adaptations of JK Rowling’s novels will surely be turned off by the changes taken by the writer, notably the delineation of Voldemort’s story that develops him into a more three-dimensional character.

The story starts with Harry, Ron and Hermione about to begin their 6th year in Hogwarts School. Harry as the Chosen One realizes that his enemies are multiplying as Voldemort continues to be more aggressive in the attacks of his Death Eaters even on London’s Millennium Bridge. Headmaster Dumbledore (Michael Gambon) introduces to Harry some key memories regarding Voldemort’s past but one of these is distorted, that of Prof. Horace Slughorn (Jim Broadbent) tackling forbidden magic. Dumbledore asks Harry to visit the reclusive Slughorn in his London home to find out the truth about the memory concerning the young Tom Riddle who later became Voldemort, as it may have a clue on how Voldemort can be subdued. But Slughorn has a deep dark secret in his past that he doesn’t want to be revealed.

Draco, Harry’s envious classmate and rival, wants to avenge the defeat of his father, so he consents to do a serious crime aimed to pave the way for Voldemort’s return. Harry fights a growing attraction to Ginny while the smart Hermione and the somewhat slow-witted Ron won’t acknowledge their feelings for one another. Ron even falls for another girl called Lavender Brown, the exact opposite of Hermione, who has her own admirer in Cormac McLaggan. “Oh, to be young and to feel love’s keen sting,” sighs Dumbledore.

Harry also has to worry about an annotated spell book signed as the property of “The Half-Blood Prince.” The ambiguous Prof. Snape (Alan Rickman) eventually shows his true colors and collaborates with Voldemort’s friends. We are also reintroduced to the now familiar other characters like the giant Hagrid, McGonagall, Wormtail, Lupin, Filch and Flitwick.

Director David Yates (who also megged “The Order of the Phoenix”) made the movie darker than the past ones. Compared to the first “Harry Potter” flick that has a cheery and more colorful look, the color in this film is so desaturated that some scenes (particularly those shot in the climactic underground cave sequence) look like it’s black and white. It’s no longer a child’s fantasy but more real-world in its treatment. It’s no longer kid’s stuff as we even see a cute waitress in a London café flirting with Harry early in the film and showing more raging teen hormones.

The sets have also been changed, with Hogwarts losing its cheery fairy tale atmosphere and becoming more ominous and gloomy. The Dining Hall, fondly remembered for its many memorable scenes, is later shown being demolished by Bellatrix Lestrange (Helena Bonham Carter) who obviously has more destructive objectives. While watching it (it runs for 2 and a half hours and manages to squeeze in another Quidditch game), you feel that this flick meanders, like it’s actually setting up subplots that will have a more satisfying pay off in the two final installments.

Technically, the film remains impeccable, with its marvelous production design, the stunning special effects, the wonderfully atmospheric cinematography, and the affecting musical score by Nicholas Hooper that intentionally avoids repeating the themes originally written by John Williams. The film ends with a big bang, visually and emotionally. For those who are not familiar with the book, they’d surely be surprised by what happens in the murderous climax. But those who’ve read it will realize that the movie version does give justice to Rowling’s written word and provides solid entertainment in what could be the most creatively and financially rewarding movie series of all time.