Those who have read the book would know that Deathly Hallows follows it quite well. There are subtle differences, but none that would distract from the overall enjoyment of the film. Therefore, if you are one of those people who were disappointed at how butchered the previous movies were to the books, then you shouldn't have a problem with this one.
To those who don't know, this film is about Harry, Ron, and Hermoine setting out to find the horcruxes that must be destroyed in order to defeat Voldemort. They don't really know where the horcruxes are, or how to destroy them. Meanwhile, Voldemort's minions are searching for them and the people that they care about are in mortal danger.
The reason why I consider this one being the best one so far (although I really loved the first Harry Potter) is its brisk pace. In previous installments, there always seem to be this lag time. These lag times usually entail something being introduced to the characters that is vital to later in the film. This resulted in slowing the films' pace. It didn't really happen here. There were some slow parts, but something would pick up the speed and usually kept the audience laughing. There's a scene where Harry and Hermoine were distraught, and Harry danced with her like an idiot. It helped lighten the mood and also brought interest to the scene.
There's a lot of action in this one, and the performances were unbelievable. I heard a lot of praise for Helena Bonham Carter as Belatrix. She did a wonderful job and a lot creepier this time around. The three leads: Harry, Ron and Hermoine all did a superb acting job this time around because their chemistry was on the mark. Also, there's an animation sequence in the film, which, at first, I thought was out of place because never had there been an animation sequence in a Harry Potter film before. It was awesome.
I also welcome back Doby. What took him so long to come back?
The only negative thing I could say about it and it's very minor is how the film ended. It just left you wanting more. But it is the first part and we would just have to wait on what will happen in the conclusion on the second part.
J.K. Rowling is probably writing a new Harry Potter as we speak.