It goes like this: the United States is no more. Disagreements about who gets to be Mr President ends in the American Civil War Mk 2 and the greatest army of all time becomes confused and starts to shoot at itself. The Europeans have - for some reason - captured Washington, and everywhere else has gone to the dogs (of war). Texas, California, The Old Confederate States, New England, The Central Plains and er, the Microsoft Zone (not really), are all at each other's throats. They must wrestle, if tanks and helicopters can be said to wrestle, to bring mega-death and vicarious entertainment to our tired gaming souls.
Your war, should you choose to spend your cash on it, is one of turn-based strategy. Yup, there's more to Shattered Union than some thinly-veiled swipes at Mr Bush and chums, even if that is enough to justify its existence to spineless liberals like me. Sure, the United States probably should be balkanised to bring about world peace, but if it doesn't make a decent videogame then it's really not doing anyone any favours.
So is it any good? Mmpf. S'okay. S'pose.