The teaser did not really convince me this was gonna be big, but the preview blew me away. I also noticed the color contrast was significantly higher compared to the trailer
Fave bit for me was the mess hall scene, Stephen Lang's character talking to the recruits about the Na'vi being tough as hell, was like i was looking into a large window and not at a screen. The jungle was also very beautiful to look at.
As for the few people ive heard say the cgi in the teaser as non groundbreaking, it has to be seen in 3D and after a few mins you forget it is cgi and you do really feel like your there and im not sure there is another film out, or coming out that is like it. I just hope people dont focus purely on cgi , thinking that's the main selling point. It really isnt. The Na'vi were believable, and yes you can tell it's CGI, I was however accepting them as fully realized characters.
The 3D is great, subtle but effective, it draws you in, non-distracting whatsoever. You notice the CGI characters have actually MASS, instead hollow CGI puppets jumping and bouncing around.
I was completely transported in this 'world'.