The Content Collection includes all of the previous Elite only content drops along with the newest multiplayer map, Black Box, and the two new Spec Ops missions. Details on the content drops can be found here.
EGM’s TAKE: Content Collection #1 offers a lot of new content for non-Elite players and finally catches them up with premium Elite subscribers. This should keep Call of Duty fans happy for a little while until the next round of DLC gets released. At which point the anger over Elite subscribers getting DLC months in front of every one else will begin again.