The question you've got to ask yourself is: With Black Ops still dominating the online gaming world, [beating out Battlefield 3 in number of players daily since launch] is it worth the extra money to play a new 5 hour campaign, get your hands on an entirely restructured combat system, and play on 16 all-new maps.
If you're bored with Call of Duty games, you'd be bored with Battlefield all the same. That is unless you're bored with CoD because you enjoyed camping, and you can't now...