A lot of it just felt unnatural. Everyone gathering outside, then the shot of every family in their backyards. When is everyone home in the middle of a given day? And how many are going to go outside to watch lightning?
Then the hole in town. The first car that thing threw, everyone, or at least most people, should have taken off running. They're still all there, though, verrrry slowly backing off, like that's nothing to be too concerned about.
In the bit with the news crew and the airplane, they're rummaging and eating like it's been a month since they last ate. It was less than 24 hours from when the aliens started rising, sheez.
The basement hide & seek went on way too long. And the aliens acted like damn morons, I can understand a bit of curiosity at human belongings, but it's ridiculous to have them be amazed by photography and a bike wheel. I'm really tired of stuff like that, if the aliens are building and piloting this advanced machinery far beyond our comprehension, they should be fairly smart, not acting like dumb animals like they were in this and countless other movies.
I didn't even think Robbie not dying was the most annoying part of the end, either (though yeah it was really stupid). It was that the family is just there waiting in their untouched neighborhood, safe and sound and not looking at all worse for the wear. It seemed rather ass-backwards that aliens were ransacking remote farmhouses and small coastal towns, but hadn't even touched a big neighborhood right outside a major city like Boston.
I think the end of the aliens would have gelled better if they simply, say, gave an allusion to people or plants being killed when taken out of their elements, due to not having immunity to region-specific diseases. The Spaniards arriving at South America, for example. Would have helped people wrap their heads around it a little better. As is, it was just "they were killed by disease. the end."
It was worth seeing once for the effects, but there's no meat anywhere else.
