I noticed a lot of stuff not present in the original 360 version.
The zombie poodle was actually Madonna, the dog that got the crazy old lady crazier and unleashed all hell. I played the original version to death (Heh...) and I never found Madonna.
The giant security cop was actually one of the psychopaths (the elephant lady who kept abusing prettier women) in zombie form. Either you get to battle them twice, once as a psycho, the other as a zombie, or if you miss the boss battle you encounter them as victims of the zombie invasion.
Finally, Adam, the infamous clown, is battling Frank on the rooftop. The original battle took place at night at the theme park within the mall. Either this is footage from the 72 hour mode or they retooled the whole storyline.
The gameplay looks to play faster and more fun and before. As much fun as it was to mow down hordes of zombies at times it was very slow, and aiming sucked balls. This sucked even more when escorting survivors.
This looks like you can easily defend yourself from zombies and easily dispose of them in a quick and fun manner.
Like S_B said, even if the game looks pretty crappy this looks like its worth playing again just to experience the new controls and the new story elements.
Consider me sold.