Then audience profiling cast its ugly head. The characters have to be cardboard clichés that we've seen in so other bad films. The old people have to be surpassed and replaced by the young. The villains just want to destroy and snarl. In the end, it just turned into a joke: a highly organised team of survivors run away aimlessly firing guns in every direction but the enemy, while a pack of wild humans attack with machetes and other similar devices, like a bad remake of the Anglo-Zulu war.
Bottom line: started good, continued bad, ended stupid. So an average Hollywood sci-fi.
Good actors like Bill Paxton and Laurence Fishburne are stuck in films like this. They do their best, but really, that is limited by the single dimension of the script. In the end they have to be either good or bad and anyway they have to die for the main, young, beautiful, incredibly stupid main characters to rise to the opportunity. Things like these make me not trust the hope of humanity surviving a disaster.