When you're James Cameron, the visionary director of box-office champ "Titanic" and you've declared yourself "king of the world," what do you do next? Simple. You create another one from the ground up.

That's exactly what he's done with his first film in 12 years, "Avatar," a gazillion-dollar CGI/3D sci-fi epic that, despite some slip-ups in the plot and dialogue, sets a new benchmark for what films can do.

In 2154, as Earth is ravaged by implied environmental turmoil, American corporations, military and scientists have traveled to the far-off moon of Pandora to mine a rare element to help save their planet from the brink of disaster. But this element happens to be under the ground occupied by the Pandora's people, the 10-foot-tall blue-skinned, nature-loving natives known as the Na'vi.

Humans have a hard time surviving in Pandora. The atmosphere is toxic and every animal seems capable of dealing a lethal blow. But Dr. Grace Augustine (played by a former Cameron heroine Sigourney Weaver) has developed a way to walk safely among the natives where humans in casket-like capsules can psycholgoically link up to half-human/half-Na'vi creatures known as avatars to peacefully convince the Na'vi to relocate to Pandora's other parts. Unlike the science geeks who previously occupied these avatars, a parapalegic Marine grunt Jake Sully (Sam Worthington) travels to Pandora to replace his twin brother on the mission and intrigues the Na'vi people with his gung-ho warrior mentality.

He gains the trust of the natives and the affection of a Na'vi princess Neytiri (Zoe Saldana), who teaches Sully about the Na'vi's symbiotic relationship with all living things, including their ability to mentally link up with horse-like creatures and flying dragons they ride.

But Sully soon finds himself at odds with the plans of Colonel Miles Quaritch (an entertaingly over-the-top Stephen Lang), who would rather mow down the Na'vi's sacred lands with military might than wait on a diplomatic solution.

Words can't begin to express how amazing the world is that Cameron has created using innovative CGI. From Pandora's floating mountains and luminescent plantlife to the Na'vi's elongated and elegant movements to the tie-dyed colored banshees, hammerheaded rhinos and leathery dog-like beasts, every aspect seems tangible and true-to-life, especially in clear and immersive 3-D. Couple this with some of the hold-on-tight feel and ambition of multiple action sequences and you have a film that ranks right up there with "Star Wars," "Jurassic Park" and "The Matrix" in its expansion of technical boundaries.

But even in this must-see experience, the flaws are also visible. At a few ticks under three hours in length, it could have been cut down to a leaner and meaner package. The dialogue (never a Cameron strong suit) is sometimes laughable and only adequate enough for advancing the narrative. This is even more of a credit to Worthington and Saldana, who are able to act through bad lines along and their CGI characters to show genuine human emotion and romantic chemistry. The film hits you over the head with its heavy-handed messages; the pro-environmentalist one from the Na'vi's standpoint or the anti-imperialistic one surrounding the oppressive military. And once you see "Avatar," you'll probably be reminded of another film where a man betrays his people after respecting the beauty of a misunderstood culture, namely, "Dances With Wolves."

Nevertheless, with a film that's overwhelming on all other fronts, those negatives are easily brushed aside. "Avatar" almost forces you to submit to its thrilling power and imagination and reminds you why in a time when home theaters are on the rise, an actual theater can be where the real magic happens.