When I look back at the HP films, from the very first to this one, the progression is obvious. There is a maturity in this 1st installment of the final film that certainly was not present in the films prior, and all of the cast was incredibly on-point. While the journey for the Horcruxes is engaging, the film does lag a bit in spots because it tends to drag out. I did like it, just wish it were about 30 min shorter.
Part 1 works as on-the-road adventure, constantly shifting positions and introducing the theme of the Deathly Hollows right off the bat. Suddenly you have the quest for the Horcruxes (I think they never say exactly how many there are) and the mystery about Deathly Hollows, something that could have been better explained, I think. But overall it successfully paves the way for the final film.
Overall, the first part of the final movie of Harry Potter saga. It's the right decision to split the movie in two parts. So we can getting along with each characters. In this Part 1 we can also see a deep exploration of each characters. This movie is a direct continuation of Half-Blood Prince. I love this movie because it's getting darker, darker and darker. We can feel sympathy to each characters. Ready for Part 2!
Cinematically, this installment is dynamite - the second act is only boring if you care for an action sequence every ten pages, which I don't. Visually striking, this may be only six-degrees-of-Hollywood-separation from Tarkovsky. Or maybe that's me imposing based on the whole, 'coming of age in the wilderness existentially struggling with hopelessness and death' thing.