If you've seen slumdog Millionaire, apparently this is like that, but Sci-Fi.
It's really more about humanity and what we do to ourselves than a treatise on an alien invasion.
The friends that I went with were entirely depressed by the movie, whilst I was elated by it. Not necessarily it's content but by the fact that it exists. I don't want to spoil, or even imply any part of the plot to anyone who may read this.
I won't even hype it. I just want people to go in and see it. It's not some epic battle, like ID4. It's more intelligent than that.
People will find holes I'm sure. People will call shenanigans on parts. It's not a summer blockbuster per se, its an action drama, that has some cliche's in it that are not treated in the cliche way (at least not to me. Others may see it otherwise).
I like it a lot. It makes me think. I miss that sometimes from movies.