The problems I have with the book are mostly character based.
Shaw does everything he can to save those under his care and stresses the importance of family. But then at the end he basically abandons them. I also don't think his reason for wanting to get Eleanor at the end felt right. I would get him going after her for shooting his boy but wanting to get her for knowing about the theft didn't feel like it was explained quite the right way. She is a danger to his family but it's not given sufficient weight.
It also didn't feel right to me that Shaw doesn't feel any remorse at all about attempting to kill someone under his command. That should be a repudation of everything he stood for.
The Eleanor is weak thing at the end didn't make sense to me either. It's true she's (rightfully) afraid of the hurricanes in the beginning of the book. But she's not just cowering in fear. She has a concrete plan of action and emergency preparedness kits for her family. She goes out into the storm to rescue their neighbor. Later on she saves her husband who had confronted a dangerous drug addict by himself (and he resents her superior ability to act in a dangerous situation). Basically she's portrayed as a strong but flawed person. Then suddenly at the end Shaw is constantly thinking of her as weak and decides she's somehow changed. Her husband also thinks she's changed and somehow no longer resents it.
And then there's the part where she takes time in the middle of a zombie outbreak to investigate her boss' son acting suspiciously instead of helping people through the checkpoint even though if they don't make it they'll be zombie chow.
And on top of that, it's obviously bad for the Shaws to steal from the bank but somehow it's cool that she then steals it from them for her family. Apparently her theory of justice is that two wrongs make a right. Or something.