The biggest problem with Halo 4 ATM is lag dampening, its pretty much cutting the whole of Europe, Australia and new Zealand out of match making. Halo 4 is an amazing game, one of my all time favorites, but this is some serious game breaking stuff when the above mentioned can not play match making on a "relatively" (never gonna be perfect) even playing field.
My friends and i (12 of us) have reluctantly decided to give BLOPS2 a try, which i'm pretty gutted about. I love matchmaking and like to be competitive, unfortunately (ATM) Halo 4 can not offer anyone outside of america that opportunity.