The indigenous species on the planet are the Na'vi - a mysterious blue-skinned race who are able to harness the communication channels. They are able to 'link' with the other creatures which not only enables a greater understanding of the world but helps to keep the trust between their world.
Meanwhile, humans have outgrown their planet - it is 'grey' - and they have come looking for the dubiously named element "Unobtanium". What the element does is actually not explained - though it is assumed that it is a super-fuel. The humans bring with them a range of machinery in order to help them obtain the element, including a large amount of firepower.
Amongst the technology is the Avatar system. DNA is taken from the Na'vi and mixed with a human host. The creature created from this is then remotely controlled by said human.
Following the death of his twin brother, Jake Sully (Sam Worthington) - a paraplegic former marine - is sent out to continue his work in the Avatar system. As the Avatars become involved deeper in Na'vi culture, Jake must decide whether to protect the species he begins to love or to obey his superior human officers and take the unobtanium by force.
Unlike other films that use that much technology and computer graphics, Avatar doesn't fall behind on the storyline. While Cameron does enjoy showing off his fantasy world - Pandora - he also enjoys telling the story of the Na'vi. Not only that, but it's a good story allowing the audience to actively engage with the movie.
Sadly, I've never seen Avatar in 3D, so I've never been able to appreciate Cameron's vision to the full extent, but in 2D - and on DVD - the graphics are stunning. The Na'vi Avatars are so like their human counterparts it's just genius. This is a very clever method meaning that it takes little effort to figure out who is who as the film switches between the two.
Although much of the alien work is CGI, this should take little away from the quality of acting that has been input. Michelle Rodriguez again acts as the scariest lady with a gun in Hollywood and Sigourney Weaver is again justifying her role as Empire Magazine's five star actress.
There have been rumours of Avatar being transformed into a trilogy and Cameron allegedly already inserted the relevant scenes into this film in order for this to happen. This would be welcomed with open arms.