I'm stunned at all the GoW love in the thread. I expected more naysayers to jump in, but I'm willing to be the first one.
I'll get this out of the way: the game's pretty good if you play co-op. It's fun, and inspires a feeling of epicness (sorry) in the player, perhaps better than Halo did. In co-op I felt like, "I'M MARCUS MOTHERFUCKIN' FENIX, AND THIS IS MY FRIEND DOM. WE ARE HERE TO KICK ASS AND CHEW BUBBLEGUM."
OTOH in single-player, it feels more like, "I'm Marcus Fenix, and this is my distinguished mentally-challenged half-brother, Dom. Say 'hi,' Dom. No! DOM! No, I said stay here! Don't run over there, clear the area from HERE, you STUPID FUCKING SHITHEAD."
Singleplayer was not fun. Attempt, fail, attempt, succeed, go a little further," lather, rinse, repeat. It's not just that playing with real humans cooperatively is better, but that Dom's scripted moments of charging the machine gun nests consistently result in his death, me attempting a "rescue," and me reviving him just as I get capped, and AI won't do you the same favor it's just been granted. So... reload from previous save point, wherever that was.
Suck. Suck. Suck.