Fans of every genre should see this movie - it really is unlike anything ever done before.
All complaints I hear about it are based on obviously personal preconceptions, not on the actual quality or content. So go! See it in iMax and sit right down in front so you can see, feel, and hear the effects. Then, stop thinking so hard and just experience the movie - it's incredible!
The messages in James Cameron's films are always conveyed with "stark reality", not relying on subtle messages or creative symbolism (they have them, they just don't rely on them). For me, this film would have held more realism had it been set in 3154 instead of 2154 - technology does grow in leaps, but they are not instantaneous.