Had I seen Avatar before I did my end of year review, it would have replaced District 9 as the best film I saw last year.
The opinion I'd garnered from the interwebs prior to seeing the film was mixed; there was a plethora of different reactions, ranging from hugely critical to gushing appreciation. It was hard to pinpoint a majority consensus, though the statement I saw most often was one along the lines of "Don't let the weak storyline and hamfisted ecological message ruin what is a visual, action-packed masterpiece."
I think that's roughly the opinion I hold of Avatar. The story itself has come under fire for being too simplistic, with the criticism that it was largely left undeveloped due to the focus on visuals. While this is largely true, personally I don't feel the film needed a more detailed story. Sure, it's a fairly simple plot, but I don't feel this detracts from the quality of the film. In fact, it can be seen as a strength - a more complicated storyline may have proved confusing and undermined the power of the film. I think the story suits the film's needs perfectly.
As for the 'hamfisted' environmental message, I didn't have a problem with it. Some viewers suggested it was clunky and oppressive, but it wasn't for me. It's there if you want to embrace it, but it's no problem if you don't. It's not like the message is rammed down your throat. In any case, I think it's a decent statement and adds a nice thematic edge to the film.
As you'd expect, the visuals are easily the film's strongest point. The world of Pandara is wonderfully realised and surely ranks as one of the greatest examples of world building in film history. I found it utterly convincing and absorbing, not to mention stunning to look at. The colours are beautifully done and there's some great ideas in terms of flora and fauna that make the film a really impressive spectacle (and the CGI is first class). These visuals, when combined with some thrilling action sequences, make for a seriously exciting watch. Make no mistake, this is a truly epic film and it is jaw-dropping at times. I'd recommend seeing it in 3D, which is what I watched it in, though I'd imagine it would be equally good in 2d (hard to judge how much the 3D elements really adds to it).
Characterisation isn't a strong point, but it's satisfactory. There's one or two cliches, but it doesn't detract from a film which is all about visuals and action - and on these two elements it delivers with ease. I very rarely make a point of seeing a film more than once on the big screen, but Avatar is probably going to be one of the few exceptions.
To sum up in one word - exhilarating.