Halo's multiplayer has always been great, throughout the whole series there have been a ton of awesome maps, crazy game modes and lots of awesome to be enjoyed.
On the other hand I practically detest every one of the campaign modes aside from the glorious Halo CE and Halo 2. I just felt like after these two games none of the levels, settings, characters or encounters were even memorable, let alone likeable. It felt like the more they tried to flesh out the setting the more silly, convoluted and even at times pretentious it as a whole seemed. Reach in particular tried to be an epic, emotional, story-driven war story, but it just wasn't.
I'm not sure what it is, maybe it's the fact that it's an entirely fictional setting rather than an instantly recognisable real world one, but I reckon that Halo tries way too hard to get you all 'emotionally invested' and give a shit compared to a lot of other similar FPS games.
Since I've completely given up on the idea that I'll enjoy a Halo campaign again, I'll probably pick up Halo 4 at some point though almost exclusively for its multiplayer. However a lot, hell maybe most of the changes they're making, namely the random weapon spawns, absence of Elites, new create a class system and a gamemode where your bases actually defend themselves so you don't have to do it yourself, all seem really dodgy, but none moreso than 343's plan to cram story into the multiplayer.
One of the biggest reasons I've liked Halo's multiplayer so much is it's complete absence of story, you don't have some 2d douchebag yelling into your guy's head every two seconds telling you to stop the bad dudes doing their bad stuff, boring-ass cutscenes don't come up every time you get to a new area, I no longer feel like the game is forcing me to care about things I have no interest in. Depending on how much they insert and try to force story elements, exposition or whatever directly in the game, it might really kill it for me. Having say, a small wall of text on the loading screen before a match explaining what both sides are doing there would be fine, but I can't help but feeling that it'll be a lot more than that, that perhaps they'll try to make the events of multiplayer matches follow some sort of narrative, starting and stopping the actions of players at certain points, restricting their freedom in-game, or attempt to tie them in heavily with events in the game's story. Killzone 3 has several multiplayer missions a lot like this sort of thing, and they feel very, very jarring.
In a whole I'd say Halo sucks in some ways but is mindblowingly awesome in others, like a lot of series. It'd obviously differ for a lot of us but I love the game first and foremost for it's multiplayer which I feel is it's strongest and most important aspect, and to varying degrees dislike almost everything else.
