Adaptation Distillation: Generally, the movie does a very nice job boiling down the novel into a good seventy minute movie, and some of the voicework is absolutely legendary (particularly Orson Bean as Bilbo, Brother Theodore as Gollum, and Richard Boone as Smaug). The only truly noticeable plot point left out is Beorn, who is totally absent.
Adaptation Induced Plot Hole: The first meeting with the wood elves was left out... and then alluded to in the second meeting as "the wood elves had returned."
An Aesop: The film's theme song, "The Greatest Adventure".
Animesque: Virtually all the animators and one of the two character designers were Japanese, some of whom went to work for Miyazaki so this may actually be more half-Anime than pseudo-Anime Animesque.
In the book, the scene cuts from Bilbo being knocked unconscious and missing the rest of the battle, to him waking up. The scene works here as an "and the battle continued for some time" passage, allowing us to pick up where Bilbo regains consciousness, unaware of what's happened or how things ended.
Moral Dissonance: When the men of Lake-town and the wood elves both demand a share of the treasure after the death of the dragon Smaug. See Headscratchers for details.
Never Say "Die": A variation. There's a lot of talk about death, but to avoid showing blood on-screen for the wee ones, slain foes spin away into Hammerspace like a sprite in a video game or a burst balloon.
In fact, Tolkien based his elves on the traditional myths about fairies, but by Tolkien's time, the term fairy had been corrupted to mean something unbearably twee, so Tolkien used the term elf instead, even though, as he well knew, traditional myths about elfs (yes, Tolkien also invented the use of "elves" and "dwarves," as opposed to "elfs" and "dwarfs," as the plurals of "elf" and "dwarf") were very different.