The Master Chief Collection launched last month on Xbox One, but 343 announced in mid-October that it was making "technical enhancements" to Spartan Ops that would cause the mode's release to be delayed until December. Today's content update adds all 10 episodes from the co-op campaign to The Master Chief Collection at once.
The Dec. 22 patch is also aimed at fixing an number of issues throughout The Master Chief Collection, including ongoing problems with multiplayer matchmaking. For example, matches will now begin only when the teams are even, and if players quit before the end of a round, they'll receive a loss. The patch also resolves an issue in which players would get stuck at the "joining session" message. Other problems addressed by the update include a checkpoint issue in Halo 2: Anniversary and overall stability of the game. You can see the full patch notes at Halo Waypoint.
343 announced late Friday night that as a make-good for the severe issues with Master Chief Collection's launch, the studio will be giving players a remastered version of Halo 3: ODST for free next spring. That applies only for people who played The Master Chief Collection between its launch date, Nov. 11, and Dec. 19.