I wouldn't like it. Does anyone really feel good killing a bunch of grunts? Probably, since they're kind of funny, and they look like weird little turtle gnomes. But now imagine doing the same thing but with humans, and without the humor. After a while I think I would start to feel uncomfortable about the idea of a video game that tasks us with killing people, especially if we're super human and in a 1vs1 battle we're unstoppable.
It's a game that lends very little emphasis to empathy unless it is in the hands of a very good writer and frankly I don't think there are many good writers in the video game industry that can pull this off.
But then again, I play Halo for the story and not the gameplay. I don't like shooting games so I'm probably the wrong person to comment on this.