I have yet to play Halo 4 (to be honest, I JUST started Halo: Reach), but if reviews keep coming up as they have been, I may not even waste my money on it..
More on topic, I just spent my whole night playing Matchmaking online with my boyfriend, and I've taken a specific liking to Firefight Arcadefight.. Truthfully, that's all we've been playing for the past 3-4 hours. (... Wow, that long? That doesn't sound healthy...)
I've begun campaign and will probably play it through when my boyfriend isn't online to play with (no offense to anyone, but he's always a first choice as a teammate.. He protects me IRL, so in-game, he's going to do the same); So I'll play through campaign on my own.. If I can pull myself away from Matchmaking.