Jake's plan made no sense!
So Jake is hailed as this genius military tactician at the beginning of this movie. In light of the events of the first movie, it is understandable. He knows how the humans operate. He knows their mentality and attitude, and of course their startegy and tactics, so he can deploy effective counter measurements, as evidenced by the tree tribe's victory at the end of the first movie. So far so good.
But Jake becomes absolutely braindead at the beginning of this movie. Let's see the facts:
- Jake knows that the primary characteristic of humans is that "they don't give up". So it should not surprise him at all that they are coming back.
- Jake is aware that Quarich is back, he even kidnaps his children, proving that there is a personal grudge / revenge angle of all this.
- Jake successfully united the tribes at the end of the last movie. So he is governing over effectively infinite resources when it comes to fighting back.
So if you were in Jake's position - what would you decide? I think just going by common sense, the very last thing on anyone's list should be "running away to a different tribe". It's stupid. It's insulting the audience's intelligence. Jake knows they are going to hunt him down, especially Quarich and his goons. That is the one thing humanity in general would be doing, as he is a prime target, so it would not make sense to run away and hide even without Quarich's involvement.
And he did not even have any other plan! I mean it was not "we will hide at the water tribe until I can amass a large enough army to fight the humans and drive them away again" or "While I am hiding, the other tribes should do guerilla warfare, perform tactical strikes on key resource lines, I will instruct them on how / what to attack". The way it is depicted in the movie, he just expected to live in peace with the water tribe... until he dies of old age? Wow, that made my brain hurt!
Also, the story is all over the place. Humanity wants a new home now, instead of just mining Unobtanium. Oh, wait, scratch Unobtanium, they are after whale juice now. I know Cameron wanted to show the water tribe and the cruelty of whaling, yadda yadda, and wanted an excuse of how to integrate the water tribe into the story. But... still you need a stroy for that. What we got at the end - after 13 years! - was just a plot outline that needed finer details, more fleshed out characters, etc.
On the positive side, Cameron still knows how to shoot an action scene, and the overall visual clarity of the movie was just awesome, especially in IMAX 3D. It was not quite as shocking technical leap as the original movie in 2009, but there were some shots and scenes where I could not even tell if there was any live action involved in the creation or not... And even considering how stupid the foundation of the story was, the plot flows (no pun intended) well, so overall the experience was entertaining - but I was mad how they sidelined Jake to focus on the kids and made him really dumb.