Since BlOps2 isn't set in the modern day or the past, the designers are left to imagine a lot of the weaponry and fighting elements of future. Unfortunately, it looks like they leaned a little too heavily on the Halo franchise for inspiration.
I'm not saying the developers "ripped off" Halo, because there is still a distinct feel of Call of Duty here, even though stylistically some things have changed. What is strange is that they chose to go down this futuristic plot path at all, especially with Halo 4 scheduled to be released a week before Black Ops II.
As LBD of GeekThingsPodcast suggested to me earlier today, the campaign of each game could play a significant role in your buying preference. And you would also assume that each game will still have its own "feel" as it has in the past.
While many gamers (myself included) will purchase both titles, one has to wonder if casual gamers will pick up Halo, enjoy it, and then a week later when BlOps2 comes out decide they don't need another futuristic shooter with laser guns.