Avatar

No, not the Bloody-Handed god, but the movie. I'll relate it to 40k, though, by the end. Just watch.

The Movie
In short, go see it.

Now, I will tell you that you have heard this kind of story before. Have you seen The Last Samurai? Catch Dances with Wolves, if you're not really in my generation? Read something like 'Things Fall Apart' in any of your English lit classes? Then you have an acquaintance with the story. The suspense probably won't keep you on the edge of your seat.

No, it's the visual effects that you're paying to see. Frankly, I forgot that I was watching a CG-heavy film pretty much off the bat. All of the creatures move realistically.

The attention to detail in the critters is pretty astounding. Other than having a thing for six legs and long-limbed aliens (...which, in fairness, you can chalk up to a lower-gravity world), it pretty much looks like a jungle. Hell, all the stuff in the jungle looks like it belongs. There's a nod towards creating a fully believable ecosystem, for example. A lot of films just don't seem to have that kind of detail in them. I mean, I like aliens. It's part of what got me into 40k: neat aliens. (Mmm, here come the Tyran- wait, I was on another subject...). Moreover, I like believable aliens. The ecosystem of Pandora reads right.

And, well, frankly, I always wanted a pet dragon-thing, but I was always afraid to ask. Plus, I'm pretty sure feeding and cleaning up after it would be a pain. Still, if you think bird crap is bad, think about training your pet to dive-bomb a rival's vehicle.

The military hardware is also pretty sweet-looking and well done. The mechs (they're not powered armor because you sit in them...) are a believable size. They're integrated in the forces believably. Hell, given the terrain, you'd not even want to THINK about wheeled or tracked vehicles. The control system is similarly intuitive: screw the joysticks, you pretty much have gloves with some braces and wires attached for the arm controls, and presumably pedals. That way, you can take someone with some infantry know-how, train them on the controls, and then just get them to realize that they're a 15-20ft tall infantryman with a redefined version of 'handheld' weapons. All the VTOLs are neat as well.

Amazingly, Sigourney Weaver is in this one without trying to kill the aliens. Then again, the aliens aren't trying to use her body as a yolk sack for their young.

And Now, That Promised 40k Tie-in
Hey, you've all heard of Death Worlds, right? Right. Well, Pandora IS one. The atmosphere can kill you in a few minutes. Gas masks are standard issue. That also makes the atmosphere the slowest killer on the planet. The native humanoid species favors a hunting bow, and if putting a meter-long stick through your heart/lungs/other important bits isn't enough, the neurotoxin on it takes you out within a minute.

And, well, the wildlife? The protagonist's first outing on the planet kind of sums it up. He's approached by a large, six-legged hammer-headed armored rhino the size of an elephant. Mind you, he's in his Avatar body, which is about 9-10 feet tall and wielding a machine gun like mere mortals wield an assault rifle.

"So, what do I do, shoot it?"
"No, no, it's territorial! Just stand your ground! And, your gun isn't big enough to hurt it."
Jake yells and makes threatening gestures. Creature runs away.

Creature runs away because there is a 12-foot-tall-at-the-shoulder six-legged armored panther thing walking up behind Jake.

Doctor's pro tip: "No, no, this is the one you run from!"

Everything else is just hungry and/or generally inimical to human life.

On the movie technology front, if they can pull off this kind of feat, then they can bring Tyranids, Necrons, or anything else in the 40K universe to life. This, of course, assumes they have the budget involved. I believe motion capture is a bonus as well.

Overall
I enjoyed the movie. Definitely see it in 3D in the theaters if you're going to see it. The story isn't bad. The story is enjoyable, but not original. Then again, a movie sells an experience, and more movies these days are about a neat experience than they are about a heady, in-depth plot. I mean, you can do that with movies, but I honestly think books are better at giving us depth, breadth, and all that stuff.*

Go see the movie for the eye candy and the thrill. Oh, it's also about two and a half hours, but you won't notice the time unless you had a hefty drink prior to entering the theater. You won't want to leave once it spools up.

*I know there are exceptions to this, but good books like the actual Starship Troopers novel, anything Dune, anything Asimov wrote...some stuff just isn't going to make the trip from several hundred pages of novel to a couple hundred pages and ~2 hours of screen time.

Maybe I'm just getting old, but I still read. On the other hand, I think that a good TV series can pull it off, but we're talking something like 12-20 or more hours of storytelling.