Just to add a little to the story of the Ents as written. Once the Entmoot began, it took 3 days until the decision was reached to go to war. Jackson probably wanted to convey that it didn't happen quickly. In the book, the Hobbits just patiently waited until it was finished. In the movie, the Hobbits were shown to be a little "Hasty." Still, it was a great effort by Jackson to capture the Ents on film. I'm sure not an easy undertaking.OK in response I am going to let my nerd flag fly high and proud. This deserves a multi-beer disucussion at the local pub so I'll keep it short and mention only 1 negative and 1 positive.
Jackson changed the Ents from wise guardians who needed only to be wakened and quickly went to war to defend Middle Earth, bringing the Hobbits with them, into indecisive procrastinators who needed to be cajoled by the Hobbits into defending Middle Earth. That was a major and very disappointing change. I nearly walked out of the theater when I saw it the first time.
One change I did like was that Jackson gave Aragorn more depth and complexity than he has in the novel.
Back to the movie Dune, much to find problems with, but still for 1984, a bold attempt to capture some of that book on film as well. Though, if viewed now, I skip most scenes with the diseased scabby Baron. That was not in the book.