From my experience with Firefight in Halo 3: ODST and Reach, it gets really boring, really fast. The only people that should be looking forward to Arena Mode are the ones that are either too incompetent to finish a raid, or don't have enough friends to form a six man fireteam. edit - one of the few things 343 did right was to replace Firefight with Spartan Ops or whatever it was called in Halo 4. I prefer stuff with a story over endless waves of enemies.