I'm a little torn with this one, because I definitely had a lot of fun playing it.
It's wonderfully addictive and time-consuming, easy to learn and play, yet still challenging. I liked some of the new abilities, namely the Taunt. I often encountered a weird bug with the warehouses, where my character would randomly walk AWAY instead of going to capture them. Aside from that, the game gave me no technical trouble. Unfortunately, like some of the others, I just don't feel this is different enough from the first Decision to be called a true sequel.
I think the lack of a proper narrative was the game's greatest flaw. There's literally no story introduction, and the character doesn't speak at ALL, so we can't really sympathize or connect to him any more. We're just left to assume he has no trouble at all continuing this mission in another city. It'd be nice to have some insight to his motivation (aside from obvious survival) for doing this, or how he's changed/grown since the previous game.
At the very least, there should be something different about the CITY to warrant a liberation. Maybe there could be an important power source here, or a new strategic weapon, or a local band of survivors that need help- just SOMETHING to make us care about it. Otherwise, everything just seem to boil down to: HERE ARE MORE ZOMBIES. KILL THEM. AGAIN.
As it stands, though, it's still a very fun game; I've actually played through it twice now. I just don't feel there's enough meat here to call this anything more than an expansion of the first.