Let's start at the very beginning. In this case, that's a big ol' spoiler alert. Please don't read this unless you have a) already seen 'Harry Potter and the Deathly Hallows: Part I' or you haven't seen it yet but want to know some of the key ways the film differs from the book. If you want to remain unspoiled, look away ... now!
For those of you who are fellow book fans, we've highlighted five different aspects of the film and graded them based on how faithful director David Yates and screenwriter Steve Kloves were to the first chunk of J.K. Rowling's epic, series-capping book.
Returning Characters: A-
How the Movie Does: Good news, S.P.E.W. members, Dobby (voiced by Toby Jones) pops up to save the day, just as he does in the monumental 'Malfoy Manor' chapter in the book. And Kreacher (Simon McBurney) also returns to reluctantly help the Trio in Grimmauld Place. We also get to see (albeit briefly) all of the pertinent Weasleys and Order members: Mad-Eye Moody (Brendan Gleeson), Remus (David Thewlis) and his new wife Tonks (Natalia Tena), Kingsley (the imposing George Harris), Fleur Delacour soon-to-be Weasley (Clemence Poesy) and the ever-effervescent Luna Lovegood (Evanna Lynch).
On You Know Who's side, Snape (Alan Rickman), all of the Malfoys and Death Eaters -- especially Bellatrix Lestrange (Helena Bonham Carter) -- emerge in full force. Cat-loving blood-purist Dolores Umbridge (Imelda Staunton) has her moment, and is fantastic once again.
Whom You'll Miss: Dean, a muggle-born on the run, like Hermione, had a pivotal supporting part in the novel, but there's no mention of him in the movie. Since there's much less time spent at the Burrow before the Trio goes searching for horcruxes, there's painfully little of the Weasleys and the Order (the movie skips right from the 'Seven Potters' escape from 4 Privet Drive to Bill and Fleur's wedding day), and Viktor Krum (Stanislav Ianevski) doesn't appear in the wedding scene, despite reports he would appear in it.
Important New Characters: A
How the Movie Does: This is the one category the movie nails as an adaptation. Casting Bill Nighy as well-intentioned but ineffective Minister of Magic Rufus Scrimgeour; Domhnall Gleeson as Bill Weasley, the brood's hunky (and scarred) eldest brother; and Rhys Ifans as Luna's equally as eccentric father and Potter-trusting Quibbler editor, Xenophilius Lovegood, is enough to earn the adaptation an A; but the movie also introduces us to Aunt Muriel, Dumbledore's old friend Elphias Doge, and a host of hitherto unnamed Death Eaters who quickly gain control of the Ministry. Thanks to the never-ending stable of excellent English actors, all of the new characters are portrayed quite right.
Whom You'll Miss: Tonks' parents Andromeda and Ted are also nowhere to be found. He's not technically new, but the werewolf Fenrir Greyback, who's so menacing in the final book, doesn't have any lines in the adaptation.
How the Movie Does: Even if you know what's happening, you'll bite your nails at the intensity of Voldemort's first kill, the thrilling Seven Potters chase, the run-ins with Snatchers, the close-call at the Ministry, and the creeptastic encounter with Bathilda Bagshot-turned-Nagini. Bellatrix's psycho sadism still lets loose at Malfoy Manor, but the torture scene is toned down (no screams of "Crucio!") -- a good thing considering how many children will go see this movie. But Yates keeps the body count the same as in the book. No one who meets their untimely end before the Battle at Hogwarts has been spared (with the exception, as some of you have pointed out, Peter Pettigrew, whose merely rendered unconscious -- at least in this installment).
What You'll Miss: Not much. All of the major life-or-death sequences made the cut.
Romantic Chemistry: B+
Ginny (Bonnie Wright) and Harry have their one passionate snog (and the added bonus of a provocative dress zip-up) on the day of the wedding (sorry, Harry doesn't have that 17th birthday party in the film), but when it comes to romance, it's all about Ron and Hermione in the final book. Every little look, touch, and word Rowling teased fans with isn't duplicated in the film, but there are definitely enough adoring gazes, protective embraces, near-touching hands, and longing, weepy looks to make it perfectly clear that Ron and Hermione are in love with each other. And of course, there's that rage-filled smackdown Hermione gives Ron when he returns. But be prepared, there is a brother-and-sisterly dance between Harry and Hermione that may seem slightly unnecessary (at least to this Ron-and-Hermione shipper), and that awful Harry-Hermione kiss when the locket torments Ron.
What You'll Miss: We dropped a grade for Yates skipping the dancing scene at the wedding (instead, they just stare at each other from across the room) and not including any of Ron's frantic sobs during the Malfoy Manor horrors.
Comic Relief: B-
While Ron, Fred and George, and Luna are always good for a laugh, Part I includes much less humor than the other films. Since Yates cut a lot from the pre-horcrux hunt, the Weasley twins only get a few one-liners -- at the very least, George's "holey/holy" joke after he's injured was kept in the screenplay -- and leaves the comic relief to Ron, who spends a lot of time sulking in this film but still says some of the funniest lines. The supporting players who play Ron, Hermione, and Harry disguised as Ministry employees also lighten the mood. British character actors Steffan Rhodri, Sophie Thompson, and David O'Hara deserve special mention for their physical comedy portraying the three teens, who've taken Polyjuice Potion to look like adults and wander around the Ministry of Magic looking for their former headmistress.
What You'll Miss: All of the jokes surrounding the 'Twelve Fail-Safe Ways to Charm Witches' book; Potterwatch, and some of the funnier bits of conversation at Xenophilius Lovegood's house.