Against my usual policy, I'm going to repost my post from another message board on the subject here:
It was a tense movie, but it was a VERY tense movie because it put you back into a similar place to where you were on September 11th; under attack, no idea what's going on, no idea when it will stop, learning about the serious reality of your situation as you go along, our cities being destroyed etc... A lot of the images of people doing anything they can to survive were similar to what we saw on that day, like people jumping off of the pier to drown in the water because they had no choice with the aliens behind them was remniscent of the people who were jumping out of the trade center when it was on fire behind them.
Obviously it is a totally difference scenario than 911, but the story has enough basic parallels that on some subconscious level it freaks you out by reminding you of how you felt on that day. I'm pretty sure that (at least for me) people wouldn't be as freaked out if that movie had come out 5 years ago.
Also, did anyone catch what I'm convinced was a Christian Boltansky reference when the clothes were all falling from the sky?
I enjoyed it a whole lot, the plot holes were minor and inconsequential as far as I'm concerned.