The decision to split Rowling's final novel into two films is understandable for both financial and creative reasons (it almost turned into three), but the result is unfortunately two excellently produced and performed films that each feel somehow incomplete.
Deathly Hallows Part I is the first to be set entirely away from Hogwarts, as Harry, Ron & Hermione go on the run from the Death Eaters & try to track down & destroy Voldemort's Horcruxes - objects in which he has hidden fragments of his soul to avoid mortality - in the process. Although it is an effective and beautifully shot chase movie, and ends smartly with the tragic return of Dobby the Elf, it ultimately feels like an extended prologue to the grand finale.
Less plot driven than its predecessors, the action moves swiftly from one set piece to the next which, while all well staged, only hint at epic. The sequence inside the Ministry of Magic is a nice, zippy, change of pace, while the sinister influence of Salazar Slytherin's locket on Ron adds another level of pressure to Harry's existence (as if the burden of celebrity, the loss of every last one of his mentors and the responsibility of saving both the magic and muggle world from the greatest dark wizard of all time is not enough, Harry's best friend has to go and turn into a gloomy jerk ass). The young cast all perform well, miles from the perpetual, plastered grins of The Philosopher's Stone, as do the panoramic views that replace the usual grand sets.
The biggest highlight, though - from a visual and plot point of view - is the animated sequence depicting the myth behind the Deathly Hallows - the Elder Wand, which Voldemort is after to kill Harry, the Cloak of Invisibility, which was given to Harry by Dumbledore (& is the most exciting feature of The Philosopher's Stone), and the Resurrection Stone - which really lends a sense of occasion to the coming finale, although Rowling could have exploited the Hallows more in the final equation, but more on that later.
Oscar nominations: Art Direction (curious, as the only notable set is the exceptional ministry of magic which was already featured fairly extensively in The Order of the Phoenix), Visual Affects