A spell was broken today. For the first time, watching one of Peter Jackson's Middle-Earth films, I laughed. Not at the comic relief - has anyone ever laughed at the comic relief in a Tolkien film? - nor afterwards, in the comforting embrace of online memes and drunken chats with friends. There's always the risk of silliness in a film like this, obviously, and part of Jackson's achievement was always that he got you so swept up in the power of the moment, it wasn't until you saw daylight that you realised you'd been investing your emotions in elves. Elves with pointy ears. Elves with pointy ears who talk like they're advertising a New Age Moods CD circa 1994.

No, this time I laughed during the film. I laughed at the cave troll which falls down dead after using its head as a battering ram. I laughed at the continual emphasis on horn-blowing, including a loving close-up of entirely spherical dwarf Bombur's big daft face inflating as he blew. The scene where Gandalf sits next to Bilbo and fidgets with his pipe tobacco for what seems like about half an hour - that's more your adult swim-style postmodern anti-humour, but it got a chuckle out of me. Oh, and the titular Battle of the Five Armies, which comes off as nothing less than the Middle-Earth equivalent of the news team rumbles from the Anchorman films. We can't fight now, Thorin's hitherto-unmentioned cousin Billy Connolly has yet to arrive! Here's a bear riding an eagle; your argument is invalid.

It was expected, when Jackson announced his Hobbit adaptation would stretch to three films, that the increased run-time would allow him to get more into the characters, deepen his storytelling. Given that there's one dwarf whose only characteristic after some eight hours of screentime is that he uses an ear trumpet, this has obviously been a failure; as for more intelligent storytelling, there's a scene in this movie which includes an audio flashback to the scene directly before it. The Battle of the Five Armies is frantic and packed and boring and hollow at the same time, with one scene cramming in cameos from Galadriel, Elrond, Saruman and the Eye of Sauron for no reason other than to show they're still around.

This is the sort of storytelling you find yourself doing when you can't remember what kind of story you're telling. An Unexpected Journey, despite the distended opening, is still clearly the best of the Hobbit films for its clear narrative lines; the story of Bilbo becoming a hero, the story of Thorin rediscovering his heroism, in neat parallel. The Desolation of Smaug added a lot of faff and fuss but by the end of it I felt like I had a handle on what the story was; the quest to defeat Smaug and reclaim the dwarves' kingdom.

And now it turns out even that wasn't the point. Smaug flies out, causes a bit of empty and unentertaining city destruction and is killed by Bard within ten minutes. That's the character who the whole of the last film was building up to, dead. It emerges that the stuff we should have been paying attention to was all that extraneous-seeming stuff about the elves and their politics; they apparently wanted a share of Smaug's loot, which Thorin had promised to Laketown, but now he doesn't want to give either of them any of it so they go to war. A fantasy battle over debt and reparations. It's basically Grace of Monaco with more believable central characters. But only just.

And poor Thorin, who I had assumed would be one of the trilogy's key characters, ends up exemplifying this "more, but in a way that's less" ethos. After being set up as the hero in the first film and forgotten entirely in the second film, he enters Smaug's Scrooge McDuck pit and immediately goes mad with greed. We know this because Bilbo literally walks into frame early on and says, guys, Thorin's gone mad. From there on, yep, he's mad. Imagine how affecting this could be if Richard Armitage had actually been given the chance to play Thorin's collapse, rather than have it handed to the audience in exposition. There's no emotion here; there isn't a moment during The Battle of the Five Armies when I felt anything other than mild, passing amusement.

Jackson's energies seem utterly sapped throughout; the messy CGI (Legolas is now a character from a platform game), beige colour scheme and unimaginative cutting between landscapes and close-ups make this easily the least visually appealing of his Tolkien films. It seems to me to be clearly his worst film all-round, and while I can already hear you saying "Oh, come on, Graham, what about The Lovely Bones?" I'd counter that The Lovely Bones has more fine moments and performances - Martin Freeman and Lee Pace are the only standouts here, though Evangeline Lilly does her best - and was, at least, a bold attempt to do something different.

It's been sixteen years since Peter Jackson signed on to adapt The Lord of the Rings. Sixteen years in which the only steps outside that realm have been the aforementioned The Lovely Bones and a remake of King Kong which frequently felt like a Lord of the Rings movie anyway. What can he do now? Even if he made another low-budget splatter comedy it would be promoted as "From the director of The Lord of the Rings and The Hobbit", ensuring it would only reach an audience who wouldn't enjoy it. As The Battle of the Five Armies slowly played out its final shot, I found myself thinking that all I wanted from him was just to take a holiday and think about what kind of director he wants to be.

The idea that I didn't want to see any more in the immediate future from a director I once adored made me quite melancholy. But what else can you do? Hope for something else like this? No, the magic is gone.