I watched this last night with my wife. I liked it more than she did, but I thought it was totally believable that different people would react differently to the coming apocalypse, and I think it showed those different people well. One thing my wife pointed out which is either biased or even racist was how the gangs destroying things were all in the city, and once you got to the suburbs everything was peaceful with no crime, etc.
I thought the leads were good, and even though my wife hated Keira Knightly's character, I know some young women just like her. I think her character's transformation was well done and I would recommend the movie rating it about 3.5-4 out of 5.