It looks like a movie of nothing but special effects. I saw the preview last week and it really told me nothing about the movie.
Then you fail at discerning story lines from trailers! Just from watching that trailer I can assume that Earth is battling some kind of native population on another planet. Dude in wheelchair has his brain traded with captured alien (possibly because they want him to infiltrate the aliens?) and joins the other aliens and falls in love with alien chick. Then because of his feelings for her or maybe all of them he turns against the humans. That could be wrong but I bet it's darn close.
That's how I saw it. If you seriously just saw "some blue people" and could not discern the plot at all then you need to either try harder or do some self-help and take a really good college literature class.

bc