If Zombies are a far deeper option than in the past and customizable like Halo's firefight and not just a survival mode like in MW3 than yes I'm buying it for Zombies.
But I gotta be honest. I don;t know enough about Zombies right now so I'm saying no. I'm buying this for the same reason half of the current pre-orders are. Everybody else is playing it. I might as well get in on the fun.