Lena and I saw Avatar in 3d yesterday with some of my family, in a packed theater during the afternoon. I thought the 3d added an extra level of immersion and "being there" which I really enjoyed, but I think even in 2d only this would have been a very major "event" film due to the really impressive world creation and especially the best CG animated characters yet seen on a movie screen. Once every decade or two a film comes along that is such a leap forward visually, or in terms of the believable representation of people, creatures ore locations that don't really exist. I'm thinking of the Lord of the Rings films (really the first one was the real leap forward, and the others just carried on from that level), Terminator 2 (the closest comparison I can think of -- a film packed with so much "gosh, wow!" visual energy and inventiveness that the audience almost doesn't mind the clumsy aspects to the story), and before that, Blade Runner, the first Star Wars film, or 2001: A Space Odyssey.
I definitely want to see this again, preferably in 3d, and I'm sure it's one of those major sci-fi event films that will earn a billion dollars, inspire sequels, make James Cameron "king of the world" again, and inspire other studios, directors, and special effects houses to create a next generation of entertainment that much closer to "virtual reality" immersiveness.
Something like this, despite its faults, puts to shame recent mega-budget effects spectaculars like 2012 and 10,000 BC.