There be dragons, here be spoilers.
It's Christmas time again*, which means that Peter Jackson, the world's most well-funded Tolkien fan-fiction author, has once again delivered his signature gift: 144 minutes of fantasy adventure. But unless a studio decides that the Silmarillion could actually make a profit, we may never again see its like.
Once upon a time, The Hobbit was spoken of as a two-film project. I don't think anyone who was familiar with Jackson's take on Middle Earth was truly surprised that we wound up with a trilogy. However, I think I can now point to the very specific reason why, for all the pacing awkwardness it created, the third movie came into being: this was Jackson's last chance to film an epic battle. His lust for on-screen mayhem, much like the Arkenstone of Erebor, drove him to such reckless madness that he took what other filmmakers might call a climax and turned it into an entire movie.
Indeed, The Battle of the Five Armies is unique among the Hobbit and Lord of the Rings films in that, apart from the introductory scene of Smaug's demise (which, let's be honest, should have been at the end of the last film), the plot more or less revolves around a single battle that takes up about half of the movie's running time (I may be being unfair on that point, as I did not check my watch, but it sure felt like it). This movie is mostly about three things: assembling the five armies, an hour or so of heroic fighting and death, and a rapid and fairly uneventful walk home for Bilbo Baggins.
The really odd thing about this movie is that it can't keep an eye on its titular character. Theoretically the protagonist is Bilbo, but you wouldn't necessarily know it from his screen time. Therein lies the central flaw of this entire trilogy: The Hobbit, in its original form, is too small to bear the weight of all the history and mythology that Jackson includes. While much of it (Gandalf's encounter with the Necromancer, for instance) is either basically canonical or reasonably inspired by canon, it is difficult to believe that Tolkien would have ever considered including those scenes in the narrative of The Hobbit. Tolkien's book was essentially about Bilbo Baggins stumbling into an epic world of myth, while Jackson's movies often feel more like an attempt to toss him out of it.
As for Jackson's more original additions, the worst subplot of all is a running joke about the greed and cowardice of Alfrid, a series of scenes of no consequence to the plot. After an initial craven outburst, the former aid to the Master of Laketown relentlessly sucks up to Bard, then spends the entirety of the battle attempting to disguise himself as a woman, shoving treasure in his bra and bleating useless dialog. No comeuppance is delivered and no character growth occurs: the entire thing just devolves into misogynistic comic relief. A tip to writers: putting a man in a dress in order to indicate that he's a coward is a sexist trope. Comparing him unfavorably to actual women (who serve no story purpose except to compare favorably with him) does not actually make that better.
Once the carnage is done, Jackson seems to rush the ending, perhaps in a belated fit of recognition that the source novel is actually really short. Upon the death of Thorin, nearly every other sub-plot of the film is dropped in the interest of getting Bilbo back to the Shire as quickly as possible. The Elves get minimal resolution as Tauriel mourns for Kili, Legolas wanders off to find himself, and King Thranduil admits that he's been kind of a jackass. The humans of Lake Town are never mentioned again, with no on-screen indication that they received the share of the treasure that they fought for. The dwarves give Bilbo a brief farewell, but the character of Dain Ironfoot (who, as the new King Under the Mountain, you would think might have something to say to the person who did so much to restore the kingdom) is conspicuously absent.
The movie still has much to recommend it. Tauriel continues to represent the sort of addition that a book like The Hobbit actually needs, and her tragedy is sincerely felt.
Thorin (perhaps the true protagonist of these stories) has a very
satisfying arc, though a more subtle depiction of his
"dragon sickness" would have improved things and made his final
redemption more credible. The much-hyped battle has its ridiculous moments (the giant tunneling worms, the bat monsters, every instant of Alfrid's screen time), but the general tone is exciting and even ennobling, as far as depictions of death and carnage go. The whole thing is a bit of a sloppy mess, but it's absolutely clear that the director's heart is in it, and so much more besides.
And of course, the visuals are stunning. After all these years, does that even need to be said anymore? Fans of the wide-pan-over-CGI-New-Zealand aesthetic will not be disappointed, though they may yet mourn the end of an era.
Some day, perhaps decades from now, the novels of J.R.R. Tolkien will again be adapted for the screen (or whatever space-age medium we've moved onto by the mid-21st century). The extent to which those new adaptations will draw on Jackson's example is an interesting question, as he and his crew have succeeded in defining a style that exists quite separately from the original work. Call that a triumph, if you will. Whatever the most hardcore fans may think, these movies were made in large part for us, but in even larger part for the rest of the world who got something very different than anyone could have expected. As for me, like Bilbo I think it's time I got back to my books.
*It was when I started writing this, and I don't feel like changing my opening line.