Halo 5 multiplayer beta available to Xbox One dashboard preview participants.
I tried to play for about 20 minutes today without getting into a single match. Every time I entered matchmaking it would immediately pop up a full list of players for 4 vs 4 slayer. Just before the level was about to load at least one person would be dropped from the game every time. Then it would just be stuck on searching for players forever with no way to back out. The system doesn't seem to be able to replace players who drop once a lobby is full.