As remarkable as the special and visual effects are this concept was grossly under budgeted even for its time, and it shows. The idea definitely peaks your interest but the delivery was not up to its potential. The story is overly complicated with too many characters none of which are given enough screen time to invest emotionally in. The tone is a bit campy and the acting is either too melodramatic or too subtle given the seemingly devastated situation the characters are in. Ultimately one must suspend a lot of disbelief in order to go along with an ending that had to be, but wasn't given any kind of plausibility.
Film is not just about storytelling, its about storytelling with the most technologically advanced form of art known to man. Filmmakers can choose to be nostalgic and use obsolete technologies or they can build up the courage to experiment and push the limits of the medium. Audiences can be equally sentimental, favoring the old and showing hostility towards the new. James Cameron is among very few group of filmmakers that dare to put hundreds of millions of dollars, countless hours and their careers at stake for an original expression. Film is and always has been a visual and audial form of storytelling, if you don't care for spectacle and sonic emersion, read books. The story is not just escapist entertainment which often associated with a kind of childish break from reality but an attempt to have an experience beyond our own and beyond man in general. It deals with strong, political themes like over-consumption, genocide, pollution and the human need for exploration and to find meaning in the world. Like Star Wars, Avatar restores a sense of awe and wonder to the world and to the cinema.