Question about avatar the game *spoilers*?

Well i bought the game yesterday for my 360 and beat it in only a few hours.Does anyone but me feel the game was just kind of thrown together? I mean the choice to betray your own kind and join the navi came WAY to quick for me to even realize what this particular tribe is about.if i hadn't of seen the movie i'd of just been Idk.you supposedly helped destroy the home tree in between the time you land on pandora and the choice but i never did any mission linking me to the world tree.Incomplete much? The "boss" fights are just fights against the same enemys you fought to get to the boss so thats Lame as hell.There was no last boss fight with falco just a cinematic and i was REALLY hoping for a romance but that didn't happen either