For those of you who have said you put in the code, or did it online through your email, here is how you get it:
1.When your XBOX is turned on hit the home button on your controller.
2.Go to the left in the menu to “Games and Apps”
3.Select “Active Downloads”
4.Select “Specialization Priority Alpha”
5.Select download.
6. DONE
Also, for those of you complaining you bought the Limited Edition and now have nothing extra to show for it, you must have known certain exclusive content would eventually become available. I will concede it happened a bit quickly, but as someone who dropped $400 on the Halo 4 console and all I got was avatar armour, GET OVER IT!
Just play the game and enjoy it, I mean, how can you not? The multiplayer is the best in the series.