Technologically speaking, this film is an achievement... however, as a film... it is ultimately a derivative and cliche-ridden spectacle.
While I did certainly enjoy the visual impact of the film, I found the lack of character development and simplistic storyline disappointing. If James Cameron had spent even a fraction of his budget securing a better screenplay and script instead of developing new video technology, this film would have benefitted greatly. I applaud his efforts at pushing the visual aspect of the medium... while at the same time chastising his generic characters and disappointing plot-holes.
In final analysis, it is truly a case of style over substance... turn off your brain and marvel at the beautiful scenery;)