Matchmaking for Co-op is more often than not a terrible experience. I play Destiny and everything but story, the nightfall, and the raid is matchmade and its almost always pointless. Nothing quite like getting into a strike and having 2 guys AFK just to get the EXP, or people who have never played a console shooter before.
Matchmaking in Halo for co-op is something that I can continue to live without, especially since its super easy to find competent and chill people to play with on GAF. I find it way more fun to play co-op with guys who are just as into the story and Halo universe as I am.