http://www.eurogamer...an-ops-revealed
"Spartan Ops, according to the latest issue of Game Informer (via NeoGaf ), replaces Firefight, which is no more. It works similarly to Call of Duty's Spec Ops mode, but with an episodic storyline played out over several months' worth of TV show season-style DLC."
Also: "Important changes have been made to the multiplayer gameplay, too. In Halo 4 weapons drop down in drop pods at random locations around the map, preventing Halo's traditional weapon camping."