The weird video on the store page really gives a nice intro to all there is to know about this DLC: This is a novelty/fun DLC and nothing to be taken too seriously.
The Hooper Shredder car that gets added is a nice car but nothing that adds much to the mix other than it's one of the heaviest cars in the game - unfortunately it sure drifts like a street car trough corners so it's feeling of weight is so-so.
Zombie killing mechanic itself is just for fun and the only point i see in it is that it encourages the player to drive outside the green arrow marked 'recommended path'. It is also a good thing if you can remember where the zombies like to pack themselves together. Challenge yourself - how many baddies can you bag?
And what about the price for this DLC? Normal price is pretty much max this DLC is worth. If you are strapped on cash but want to expand RwR cheaply then i would recommend grabbing the other DLCs first - starting with Miami. This one has it's place and i like it - but dont start with this.