I hope I'm not alone when I say this:
I don't know what it is – it could be the less-than-what-we're-used-to feedback when shooting the Covenant as Ghal described, poorer AI, or the fact that I'm not feeling any challenge whatsoever, or some other factor – but the combat in Halo 4 is...boring (so far). I am very disengaged from how I deal with the Covenant in this game, unlike past Halo games (even Reach). It's why I'm very much looking forward to (hoping) that the Prometheans really shake things up.