The first ten minutes of this film -- on a purely cinematic level -- are some of the best in the entire Harry Potter film series. Beginning with a *rusting* Warner Bros level that helps to set the mood, followed by a rousing speech from Bill Nighy's Minister of Magic, Hermione having to wipe her parents' memories (for their safety), and Snape rendezvousing with Voldemort and the other Death Eaters for a creepy set-the-stage meeting--all to some of the best music in the entire series, courtesy of Alexandre Desplat.
Of course, this is kind of one of the more infamous films of the Harry Potter series--for being the drawn-out prelude to the finale where supposedly not much happens, for being a Part 1 in general, and for being the one where Harry Potter and friends go camping. So such compliments in the first paragraph may seem a bit much.
Here's the thing--it was a good idea to split this movie into two. Not just for the sake of the cash-grab, but the book is done better justice this way. Because it's a very long book, and a lot of important stuff happens in it. You couldn't have squashed all this into even one 150-minute movie. The final battle in Part 2 would've been very rushed. All the various plot twists towards the end would've been rushed, and some "less critical" ones might have even been left out. And how could you squash the hunt for about four or five Horcruxes into one movie? If you're still annoyed by all of this, you can blame the author for writing the book that way. (And even then, not quite everything got done proper justice--namely Dumbledore's past that comes to light in this book/movie(s).)
And actually, a fair bit happens in the first hour of Part 1. Aside from what was previously mentioned, we get a pretty good action scene early on involving the "multiple Harry's" gambit, and we get a pretty awesome Ministry infiltration scene, which also shows us Voldemort's grip on the Wizarding World (via his pawns) starting to take full effect in alarming fashion.
It's after that first hour where the whole "camping trip" starts, and things do admittedly get pretty slow-paced here for a bit. Here's the thing, though--unlike other installments in the series, it's kind of by design here--if that makes any sense. The idea is to instill the dreariness of the situation over lots of minutes of runtime, and to further explore the relationships between the main trio--which is done decently. It does feel like it could've been cut down a bit at times, and the slow pace just might be too much for some expecting more action in a penultimate film. That said, things do kick up again in the final 20-30 minutes, and a lot of interesting/exciting stuff happens there; the origin story of the Deathly Hallows stands out due to it being told in a unique animated style.
Deathly Hallows Part 1 is, in other words, actually pretty good. The pacing may not be what some would like, but it kind of works in context. And David Yates continues to do a good job at directing. There were a few changes in director early on in the franchise, and I feel that having the same one down the stretch only helped the series.
And now for the obligatory paragraph about the cast. There's actually not a lot of new faces with important roles in this one. I mentioned Bill Nighy earlier, but he's only onscreen for about five minutes. John Hurt gets arguably even less to do. Rhys Ifans fares better as Luna Lovegood's father, though. With regards to returning members, Helena Bonham Carter gets more deliciously over-the-top in this one. Ralph Fiennes as Voldemort is a welcome menacing presence after being gone in the previous movie. Jason Isaacs is also back as Lucius Malfoy, and he does quite well in portraying a more disgraced, desperate version of the character. And of course, Radcliffe and Watson are good as always.
This probably won't ever be remembered as one of the better Harry Potter films. And that's fine, because it still really isn't. But it's still not one of the worst either--for example, this is certainly better than the previous installment, Half-Blood Prince. And it still does a good job of setting some things up for Part 2. Not really a whole lot more that can be said; this film plays its role, and I guess your opinion of this film might depend upon your opinion of that role it plays.