Just wasn't what I was expecting.
There's another thread somewhere in which another poster here said that they were afraid that they showed all of the main good parts in the previews, like they did the movie 2012.
I think they were pretty much dead on.
Overall, it was more military action than alien in my opinion.
I thought there would be battles in the air from out jets vs their ships/ufo's, and more things like that, but there were basically none and it was pretty much just us fighting them on the ground with gunfire...