1. Technologically speaking, It is a Masterpiece - When you look back at film history, it is very hard to pinpoint specific films as a "the one" that changed the way films are made. This film will. While watching the film I thought to myself this must be what it was like for film goers to watch "The Wizard of Oz" for the first time. James Cameron didn't just create a film, he created an entire world and anyone with the slightest interest in film making or film history should be a part of it.
2. IMAX 3D - It is the ONLY way to see the film, so if you are planning on waiting for the DVD - don't bother. The film was specifically made for this type of screen, so watching it any other way is almost a disservice to the genius behind it. I personally, find 3D films very difficult to watch - Avatar gave me a 48 hour headache and yet I don't regret watching it this way.
3. Giovanni Ribisi & Sam Worthington - There is a lot of discussion over whether Cameron's "performance capture" technique should really be considered "acting", whether or not you say yes or no - there are still great "traditional" acting to be seen. Ribisi is awesome (as usual) as the films antagonist, while Worthington was just as awesome as the films hero. I am quite excited to see where their careers take them after this film.
4. The story is classic - It is a weird phenomenon that a film this gigantic is better liked by the critics than my friends. Most people I know claimed to hate the film (some even walked out) - most of the complaints being that the story was generic and boring. Most of the critics that I follow praised the film - noting that the story, although generic, is largely overcome by the special effects. I find the latter to be true. The story is not original - but neither was Titanic. Whether you love or hate James Cameron, you can't deny that his specialty is turning a mundane story into a spectacle. My biggest complaint is that he presented a world that was very black and white - not the many shades of grey that make life complicated. This was also represented very literally by it's racial overtones - the evil in the film was represented by Caucasian, male American soldiers who blindly kill on command, while the only soldier who questions the morality of it all is a Hispanic, female soldier.
5. It is not "Titanic" - I think that the only reason people that I know are so disappointed by the film is because they were making this comparison. It is nothing like Titanic. Here is why:
1. I would never watch it again.
2. Sam and Zoe are no Leo and Kate.
3. There is no depth to any of the characters.
So, while the film has the creative mind of James Cameron it is still missing the 3 key ingredients that Titanic had. Titanic had this "coolness" to it that made you want to watch it over and over (and over and over...). The dialogue was witty, the characters were multi-dimensional and Leo and Kate had instant on-screen chemistry. They made the world fall in love with Jack and Rose.