Producer-writer James Cameron has been nurturing a screen adaptation of Kishiro Yukito's manga series Battle Angel Alita almost since it was first translated into English in the 1990s. And this is perhaps why Alita: Battle Angel - the every-so-slightly-worse-named feature that has finally emerged from that years-long dream - feels so much like a film that was completed in all its particulars sometimes around 1999, and has simply been waiting for visual effects technology to catch up with it. The world design, the character types, even the way that the story has been smushed together from several volumes of the manga with little interest in smooth narrative flow, all feel oddly backward-looking. So does the fact that it's a film from the producers of Titanic (Cameron and Jon Landau) and the director of Desperado (Robert Rodriguez), though I'm sure it would prefer we think of it as a collaboration between the producers of Avatar and the director of Sin City. Which I must point would still make it a decade out-of-date.

The point being, Alita is sort of a square movie: joyously square. Every film with a Cameron script is kind of square (he co-wrote this one with Laeta Kalogridis), of course, with big slablike appeals to emotion, and this is hardly an exception. Hell, it might even be an exaggeration. Alita herself is notable first and foremost for her massive anime-style eyes, which take little bit of getting used to (depending on who you listen to, it takes more than the film has to offer), but which have the effect of making her expressions bigger and more palpable and plaintive. She's like a puppy dog has been inserted into the body of a super-powerful warrior robot. And that feeling is reinforced by the story, which is so lumpy that it doesn't fit together very successfully as any kind of dramatic object (it only comes into focus in its last handful of scenes, when it sets up the stakes for a sequel that is, I suspect, very unlikely to get made), but it does fit together as a series of anecdotes about a sweet-natured teen girl finding her footing with the help of a doting surrogate father and cute, sexually unthreatening boy.

The point of all this is that Alita is deeply amiable and sentimental, and it is also extremely glossy and spectacular, and this is a weird fit by any standards, though somehow it feels weirder in the 2010s, when expensive studio films are carefully and precisely buffed and polished, than I think it would have in the much goofier 1990s. It's a weirder fit than the film can completely survive, though the spectacle is pretty fucking fantastic, and the sentiment is well-served by an extremely strong, overqualified cast. If it had been placed into a screenplay that wasn't so hellbent on stopping and starting its narrative every thirty to forty minutes, we might have even had a new popcorn movie classic on our hands.

So anyway, about that cast. A lot of people are doing interesting small work, like Jennifer Connelly as a villain given far more character moments than pot moments, or Mahershala Ali as a villain given no character moments at all, though the way he navigates the mechanical requirements of a tricky part is pretty impressive. Smaller still, Jeff Fahey runs away with the film in his very small couple of scenes, barely more than a cameo, but a blessed reminder of how an interesting character actor can breathe life into a non-role basically just by inhabiting the space in front of the screen. Christoph Waltz, as the kindly but secretive robotics genius who finds and raises Alita, is securely in his comfort zone, but he's effective enough for the needs of a gooily sentimental role in a popcorn movie. Keaan Johnson, playing the cute boy, is... not enough to derail the movie, anyway.

But really, the only cast member who matters is Rosa Salazar, playing Alita via motion capture that represents some of the best CGI work I've ever seen in a movie. And we'll get to that, but I think it's worth foregrounding how extremely good Salazar is in the part. Alita is not, to be clear, one of the all-time great dramatic roles, and Salazar's challenge as an actor largely consists in ticking off a whole lot of boxes with labels like "earnest amazement at eating chocolate for the first time" and "impetuous teenage rebellion" and "bumbling flirtation with the cute boy that has no personality" and "rattle off ice cold one-liners while vivisecting other robots". And that's where this is actually interesting: the character, in finest manga tradition, is basically a nice, earnest teen girl who is, frequently, thrust into the role of being an inhumanly powerful action hero. Stitching those two things together is not, I suspect, as straightforward as it sounds, not if the earnest teenage bits are to survive the aftermath of seeing Alita e.g. use blood as war paint (not blood she was herself responsible for shedding, but it's still a pretty startling, dark moment). Salazar's eager voice, beaming facial expressions (augmented by the giant CGI eyes), and loose-limbed physical performance make for an Alita whose guileless and charming even when she's waxing rhapsodic about becoming a more unstoppable killing machine.

All the sentiment serves the film well, but the main selling point is of course its visual opulence, and this, at least, is more or less flawless. Not every single visual effect is as superbly-executed as Alita, who leaps over the Uncanny Valley to boast, hands-down, the best CGI human face I've ever seen; but there are so many obvious effects shot that the mere fact that the film only has a relative small number which look slightly underbaked is itself kind of an achievement. Rodriguez and Cameron and company have assembled one of the most sprawling, detailed post-apocalyptic worlds that modern effects technology has yet tried to create, in which the sheer glut of details around the edges becomes its own storytelling device. As guided by production designers Caylah Eddieblute and Steve Joyner, the decaying future version of what just barely reveals itself to be the corpse of Mexico City is now a jam-packed assemblage of dozens of recognisable cultures and design mentalities, all assembled from scrap parts. It's a messy but comprehensive world design that's delightful to look at and puzzle out, which helps join the film together when the script keeps taping on new narrative detours.

The film's not particularly inspired beyond being impressively designed; while he gets fine work out of his actors, Rodriguez is strictly playing the journeyman hack here, only really bringing out his own personality in a sequence during the, like, fifth or sixth act, or something, when Alita plays a future death sport called motorball. And as impressively fast as this is, with a remarkably free sense of how to use the virtual camera, it doesn't help that this is also probably the most inessential of all the film's threads. Or at least, the one that has been incorporated with the least grace. Anyway, the action scenes are generally fun and imaginative, and blissfully easy to follow with clear cutting and a comfortable use of shot scales to keep our focus on the right parts of the fighting, but they're also action scenes that I feel compelled to praise for their clear cutting. The film is charming and delightful but it doesn't soar; it's intoxicating and heavy, more of a thick dessert wine than a bright champagne. And by all means, let me not quibble with this amount of fussy detail and impeccable craftsmanship! There is surely a more playful Alita than this one, but even so, the film we got is an awfully fun time, and the sort of well-built froth that I dearly wish we had more of in our current popcorn movie climate.