This is one of my favorite OPs.
I can't speak to the multiplayer, though: I was never really in to Halo multiplayer, and the most fun I had with 4 was in custom games. For me, it was all about the campaign... which didn't work very well. The level design, as gorgeous as it was, often didn't make for good combat, the health and checkpoint system weren't very nice... it just didn't feel that good to play. Plus, there were some severe story issues I'm pretty sure I could have pointed out early on in the script.
When I'm sitting there, in my house, and a friend or family member goes "hey, want to co-op?" I consider Halo 4, but I always come to the same conclusion: Nah. I don't really want to do this. Sorry. It's not that fun. I'd rather go play Reach, which has some amazing, amazing co-op. Halo 4 looks and sounds nice, but that's all they've got going for it: the level design just isn't that good, and Heroic no longer feels like it was designed for me, as a player, to play. It's become harder, but Normal is still too easy.