This patch is supposed to include fixes for matchmaking search times, match search successes, improve lobby functionality, hit registration, matchmaking ranking, and more. Oddly enough, the studio is also rethinking its plans on the need for a public beta to test patches prior to release.
As this update contains the biggest changes to the Matchmaking system yet, we’ve identified that additional time and testing is required, and we are currently evaluating both timing and need for a CU beta with the Xbox One Preview program, as well as the final public release date in February.
(via Halo Waypoint)