There's your problem right there. It wasn't an action/adventure book. It was actually rather introspective in most places, and there wasn't a single outstanding hero or heroine in the thing - its premise was that this was how ordinary people dealt with the situation, how some became heroes and some did not; its structure was that of oral history, and it was necessarily episodic. Turning that into an action shoot-em-up with Bad Brad saving the world would be like turning Studs Terkel's The Good War into an Arnold Schwarzenegger movie. What you get won't be anything like the original, and evidently it wasn't.
I'm not surprised that the ending was a problem. In the book the war wasn't even over yet. Time for a rewrite, a deft rearrangement of scenes, and a large write-off.
Nothing better than a good zombie apocalypse movie. I’ll see it for sure, but not at the movies, or even pay-per-view. I’ll see it when I can get it at redbox for $1.50
But in the six years since then, the film went through a complete rewrite by Matthew Michael Carnahan (The Kingdom) to make it fit into the action genre more readily.
My wife likes the Colin Firth version from PBS. I could have used more car chases. And a few characters needed to die. Horribly.