After all those months of steadily-increasing anticipation, it seems that many folks needed just the two minutes it takes to view the newly-released trailer to dismiss James Cameron’s Avatar as the biggest cinematic let-down since Jar-Jar Binks first slithered his way onto the silver screen. Because while the likes of Spielberg and Ridley Scott were reportedly left drooling by the footage they saw of the Terminator and Aliens writer-director’s forthcoming science-fiction epic, the relatively modest amount of effects-action on show in the teaser has been enough to prompt significant numbers of civilian movie-fans to already cast negative judgment on the project – a primary complaint seeming to be that the much-vaunted synthespian characters are rather less photorealistic than Cameron had thus far led us to believe.

Yet if the CGI exhibited the trailer has been a minor victim of expectations so high they could tickle the soles of the Almighty’s feet, then there also appeared to be hints of treats in-store when Avatar is finally released on 18 December (particularly the big airborne dust-up between the tooled-up humans and the Na’vi residents of the alien planet Pandora). And anyway, yesterday’s trailer was a mere apéritif offered up by the living monolith that is the movie’s marketing campaign – for today represents the real main event. Yes, Friday 21st August has been designated as ‘Avatar Day’, and special screenings have been taking place, giving we lucky golden ticket-holders (actually it was a printed-out email) the chance to view a full fifteen minutes of ten-foot tall, blue-skinned alien action.

So picture the scene; there we all are – having been frisked and fondled by the movie-house bouncers, and reminded for the nth time that they would really prefer it if we didn’t whip out our camera phones and start filming – and finally we are ready to begin, and finally the 3D projectors begin to roll.

We are first treated to an introduction from James Cameron himself. And, dare I say it, the notoriously ornery auteur is looking as deliriously ecstatic as I’ve ever seen him. In fact, he’s almost smiling. He advises us that all the scenes we are about to see are from the first half of the movie and consequently there will not even be the merest hint of a spoiler. To be expected, I suppose. And with that, Jim vanishes (no doubt to go yell at an underling) and we are in proper Avatar-viewing business.

We are advised we are “not in Kansas anymore”. A narrative reference to the danger-filled world of Pandora certainly, but surely also a sly nod to we viewers about the progressive technical nature of the footage we are about to see. This first scene is a stern lecture from Corporal Miles Quaritch (Stephen Lang, sporting tramlines Vanilla Ice would have been proud of), advising a hushed audience of the perils of Pandora. As he talks, paraplegic ex-marine Jake Sully (Sam Worthington) trundles into view – just in time to hear Quaritch matter-of-factly announcing that it is certain that some of those present will not survive their venture onto Pandora. It’s not the usual holiday rep spiel, but you have to admire the man’s honesty.

Next scene, and Jake Sully is hauling himself into a high-tech sarcophagus, under the supervision of Sigourney Weaver’s Dr. Grace Augustine. Neat 3D graphical arrays are tinkered with, and a link is established between Jake’s brain and that of his avatar host body. The camera zooms in on Jake’s cranium and we take a brief psychedelic voyage down a lurid mental light tunnel, emerging into a woozy POV-shot, masked medics leaning over us. We now get a good look at Jake in his Na’vi host form, and some of the doubts fostered by the trailer immediately begin to fade – the detail of the blue-hued body’s facial pores, forearm veins and metatarsal bones looking impressively convincing. Revelling in his restored mobility and newly-bestowed physical strength, Jake ignores the calming pleas of the physicians and stalks out of the laboratory.

The action switches again; this time to the lush rainforest surface of Pandora. The 3D becomes noticeable now, with butterflies and falling leaves flitting through the space between the screen and the audience. Jake (in his Na’vi form, as he is for all the remaining scenes in this preview) faces off against a creature which appears to be some kind of triceratops-hammerhead shark hybrid, with bird of paradise-plumage fanning out from the top of its skull. That behemoth is warded off, but Jake immediately comes under attack from a far more hostile predator. A frantic chase ensues, with the fleeing Jake seemingly about to go tumbling right through the front of the screen in some shots, before he finds himself pinned under the gnarled roots of a tree. The beast snaps ferociously at the cowering Jake, sending 3D splinters flying out from the screen.

Next up is the first appearance of the female Na’vi named Neytiri (voiced by Star Trek’s Zoe Saldana), as she uses her aptitude for archery to rescue Jake from a nocturnal attack by a swarm of smaller creatures. As we see the nighttime forest luridly illuminated, the CG spectacle for once appears somewhat overwhelming and unreal. Yet the small details still manage to impress, such as the tactile quality of Neytiri’s braided hair. The next scene follows closely in on this one, again being a two-hander between Jake and Neytiri. He tries his hand at a bit of flirting, determined to prove he is not as useless as she clearly thinks he is. He seems to make some headway, demonstrating once again that block-headed persistence is the best way to woo a woman, even two-hundred years in the future and thousands of light years from Earth.

And for the finale, we are treated to an extended bit of showpiece spectacle, as Jake – face now daubed in orange war-paint – precariously balances alongside Neytiri and her fellow Na’vi on one of the Laputa-esque floating islands that hang in the Pandoran sky. He is apparently submitting himself to some form of initiation ceremony, with a now-sympathetic Neytiri watching on with worry as he attempts to tame one from the massed flock of Pterodactyl-creatures grazing on the island. After a dynamic struggle, he overpowers his quarry and hauls himself astride it, before launching into another impressive 3D sequence – Jake and his new steed imperiously soaring through the clouds.

The preview concluded with a few snippets from the trailer (the scene of the exoskeleton-clad human marines barrelling off their troop carrier looked excellent in 3D) and that was it, aside from a reminder to go and actually watch the movie when it opens on 18 December.

So, from the witnessed footage, what do we make of the prospects for a completed Avatar? Is this a movie that is going to spin the minds of the audience three times round Jupiter and then back again? Er, probably not. Is it set to be the greatest leap forward in filmic expression since Orson Welles decided William Randolph Hearst needed taking down a peg or two? Not quite. But does it look set to be a visually exciting picture, with interesting employment of the 3D technology, and a semi-coherent plot to hang all the CG razzle-dazzle around? I think it does.