Avatar is both magnificent and ordinary.
It is lush, full of colour, light and wonder - truly beautiful and with 3D more fully realised than any 3D I have experienced.
It is exciting on the superficial level of explosions and killing sprees.
The story however, is rather ordinary. For the majority of audiences who want an adventure flick with their Jaffas, I am sure it is an extraordinary experience. For someone who appreciates some depth and interest in characters and a story with surprises, there may be some disappointment. Some guy goes native and falls in love and has to fight his own people...been there? The top boss solider is a cardboard cut out bad guy with no soul, no real motive and stacks of guns.
Still, I wouldn't say don't go. I expect if you don't see this movie in 3D at the movies you will have to spend the next decade explaining why you weren't there.