Let me start off by saying I have never even picked up a book in the series by J.K. Rowling. I have seen the movies, and offer up my opinions on the movie only; no books involved, so you won't hear any comparisons to anything but other movies in the series and movies in general.
In the latest installment in the series, we find Harry, Hermione and Ron back at Hogwarts in a dark new world of dread, death and the opposite sex. While battling things every high school kid goes through, Harry must also embrace his role in destroying Lord Voldemort once and for all and also find out who sides with Dumbledore and Harry, and who has sided with the Evil Lord.
The movie opens with an astounding display of special effects as Voldemort extends his evil ways to the real world, showing us that nothing is safe, not even the world we know and love. Afterwards, we are transported back to the world of magic with Harry in tow and the wizarding community up in arms, wondering whether anyone can do anything about the return of evil. We are reintroduced to Dumbledore, who is working with Harry to find out what is happening with Voldemort. At this point even the mighty Dumbledore needs help, and he turns to a more sturdy hero in Harry to help put a stop to the evil.
While the special effects are absolutely incredible, the real jewel of this movie is the characters and the amazing changes they have gone through to get to this point, along with the amazing changes still inside them. Hermione (Emma Watson) has grown into a confident woman when it comes to magic, but we find her unsure of her feelings, especially when it comes to Ron Weasly (Rupert Grint), who finally has a moment in the spotlight but doesn't know what to do with it. Ginny Weasly (Bonnie Wright) is so much more than the fragile little girl Harry saved in the Chamber of Secrets. She has evolved into a loyal supporter of Harry's, and possibly something much more, despite having Harry's best friend as a brother.
Dumbledore, played expertly by Michael Gambon, has changed as well. The once almighty king of all that is good seems to have weakened, and seems less certain he can defeat the evil that has come. He works with Harry more as an equal than a student, calling him a good friend and helping Harry complete the transformation from scared boy and reluctant hero into one who fully embraces his role as the world's savior. He has become a truly powerful wizard, not just a lucky kid.
Possibly the best characterization in the film is that of the villain Draco Malfoy, played superbly by Tom Felton. Draco has also evolved from the spoiled brat that was Harry's nemesis. He has grown darker and attracted the notice of Voldemort, who calls upon Draco to do something even Draco struggles with, and in that struggle is a great bit of acting that leaves the audience wondering if Draco is the dark, evil character we know, or something else.
Then there are the hormones. All the characters are struggling to control them, leading to much conflict especially in a world of love potions and magic. These struggles provide some comic relief, the only bright spot in an otherwise dark world, and show that love will be the thing worth saving. (And the part where Harry gets a little lip action is great.)
We also have Severus Snape, played by the immortal Alan Rickman. This character has not truly evolved, but this character is by far the best in the series. The audience is never sure as to the intention of Snape, and whether he is good or bad. At the end, there's apparently an answer, but it amazes me that throughout every Potter installment I'm still not sure what side Snape is really on, a testament to the writing and the actor.
If there is one small complaint I have, besides the realization there is much more to the story we are not seeing, it's the small part played in the movie by the titular plotline. The Half-Blood Price story is lurking in the background throughout the first three quarters of the movie, and seems to be dismissed, and never fully explained. I also found it odd that Voldemort, the main bad guy, does not make an appearance. While this may be to increase the suspense of the impending showdown, it leaves me kind of annoyed that you never see the puppetmaster pulling the strings.
So, after all that praise, you're wondering about that Empire remark. As the sci-fi geeks pull out their weapons, let me explain that the comparison is due to the high quality of the storytelling and the tightly woven characters in what has become a huge universe. The ending shows a grim world full of darkness and despair, and only one small ray of light in Harry. Now if we can only avoid the Ewoks in the final chapter.
Overall, this was an amazing movie experience. I would recommend you catch up by watching The Chamber of Secrets, as there are plenty of references to the movie, along with the more recent Order of the Phoenix, because the movie picks up shortly after that one ends. Overall, I give this one 9 "stupefies" out of 10.