I hate to be one of those people, but today I am going to do it. The movie was no where near as good as the book. MAJOR BOOK SPOILERS -----
The movie to me gutted the character of Henry. Granted Henry was more of a puppeteer even in the book, but the setup of his character was just plain cooler in the book IMHO. Henry saves Abe as Abe is attacking a vampire - not Barts. He does take care of him and nurse him back to health, but in the book Abe knows precisely what Henry is off the bat. In the book, Henry was a settler from the Lost Colony. Virginia Dare and company die because there was a vampire in their midst. Henry does lose his wife was result and becomes one of the undead. In the books, however, vampires can kill one another and Henry joins league with other vampires that are out to eradicate their own kind.
I did not like the addition of Adam and his sister. In the book, the vampires were more of a faceless threat and I liked that. They were puppeteers using the historical characters to do their bidding. The plantation plot was much better played in the book, as Abe was lured to the plantation in hopes of killing Jefferson Davis.
The vampires cannot kill eachother bit was necessary for the movie I suppose. In the book Henry has other vampires serving to help keep Abe safe as president. When Abe is trapped in the plantation house, it is Henry and the arrival of more vampires that help turn the tide in the fight.
I suppose the greater motivations of the vampires fighting for one side or the other would have bogged the movie down. But the characters came off very one-note compared to their outing in the book.
However, I can see how the movie with its shortened time frame, used the narrative to focus on the vampire hunting escapades of Abe and his friends.
But as a person that studies history, the lesser use of the historical characters and the introduction of Adam and his sister as the big bad, just brought down the story for me.
I liked the use of Jefferson Davis, Stephen Douglas, and the intricate inverweaving of history and fiction.
The horse stampede scene was ridiculous.
What I liked about the film...
I thought the movie did a good job of capturing how the vampires were using slavery to setup a new empire for themsevles in the South.
I loved the battle scenes. As a Southerner, I thought the author's use of the Rebel Yell as the inhuman cry of vampires was genius, and the movie captured the helplessness of the soldiers when faced with an enemy bolstered by vampires in the ranks. However, I thought the whole silver subplot weakened the story. In the book I took it that the determination and will of the people to overcome evil was what won the day - not flinging Granny's silver at the foe. (I don't recall the vampire/silver link in the book.)
The death of the little boy was heart rending in the movie and the book. The book did a great job of Mary's descent into madness as she lost her kids and then Abe. If memory serves only Tad reached adulthood.
The actor playing Abe did a fabulous job. He was just superb.
The actions scenes did play well.
The movie attempted to highlight Abe's pathos and I think they did a pretty good job of showing how the war weighed on him. The fate of a nation on his soldiers combined with the death of his sons pulling Abe down was a really compelling part of the book.
Major Spoiler for the end of the book......
I don't know why they did not continue the story at the end of the movie like they did the book? At the end of the book, Henry turns Lincoln. Lincoln then fights on until the 1960s to make sure that the last remnants of the vampires are wiped from the USA.
I also liked the subplot in the book that John Wilkes Booth is a vampire. Then Henry helps hunt down JWB and kill him.
I liked the addition of Harriet Tubman. (I don't recall her being in the books, but my memory is often treacherous.)
I also liked that like Mary Todd Lincoln got to be a little badass. In the books she never knew.