I'm in the same boat. It's nice to see 5 with run at 60fps but I swear I wont play a minute of multiplayer if there is still a jackpack. That thing completely ruins slayer for me. To me the reason why Halo was so great was that it takes skill to play. The pistol 3 shot or the BR 4 shot took skill to land while straifing and jumping. Now you can get kills skill free by flying through the air and holding down the trigger on the AR or surpressor. It completely ruins the dynamic of the game imo. I realize there are people who disagree with me on this, and that's fine. Everyone is entitled to their opinion. Just realize you're in the minority and this is one the reasons why Halo is getting CRUSHED by COD.
Another would be the unlockable items. Not the items themselves (who doesn't love new armor?) but the grind you have to go through to unlock them. I know the hardcore players will go through it, but again sadly they're the minority. Most players want to feel they're accomplishing something a little faster.