For a start, as much as Nicolas Cage comes across lovely and harmless in real celebrity life, his acting is always a bit tongue in cheek. He's very melodramatic and almost has a sense of subtle comedy about him, so you can never take him all too seriously. With this thought in mind, it doesn't bode well that a movie with an 'end of the world' theme to it involve his acting, especially a lot of heroic scenes. You're almost cringing throughout, but trying too hard to take this topic as seriously as possible - This being near impossible considering the ludicrous storyline.
It's very bitty. It contains elements familiar to horror movies such as the isolated house, or a creepy girl. It involves a lot of sci-fi type characters such as MIT teachers. And then brings in a whole lot of action. It should mix together quite well, but this just doesn't. You're reminded of The Day After Tomorrow a lot in this film, but with the special effects being quite shoddy (apart from the last 20 seconds) it just seems like it's the younger brother trying to live up to the older sibling's success, but not doing so at all.
The ending to this film is pretty dire too. It's depressing, it's unsettling, it's just boring and leaves you feeling baffled by what you've just witnessed. It starts off quite slowly as well; it goes to build up to a huge plot line, and then just disappoints by fading to black. Anything involving aliens at the end of a movie is never good unless the whole movie has been focused around them. Take the latest Indiana Jones movie; the film was awesome right until the very final scenes when the aliens pop up. Utterly pointless. This does exactly the same thing, and also tried to make some sort of futuristic Adam and Eve out of the two children... Pretty darn weird.
How can one director go from I, Robots to this? Alex Proyas knows how to make sci-fi movies but he's totally messed this one up. Okay, I guess it's quite a unique storyline but that really doesn't make this any better. He should have stuck to a pretty safe narrative and made the movie out of this world, instead of taking a plot that's quite interesting and making it into something of a wreck.
There are SOME redeeming factors though. The children are quite good little actors, and when a disaster does strike it's quite intense to watch. The film doesn't stray away from watching people die either which is quite unusual. It has all the elements to be good, but this one just isn't.
Watch The Day After Tomorrow again, you'll feel a lot of satisfied by watching that than watching this.