The equipment's actually useful...
Much hyped before the multiplayer beta and much disdained afterwards, Halo 3's equipment seemed like a nice idea that just didn't work. Bubble Shields made you a sitting duck. Power Drains hurt you more than they hurt your opponents. Gravity Lifts were nothing but comic relief.
In the campaign, however, your fragile life will depend upon the new gear. Surviving to the next checkpoint is often impossible without throwing down a Bubble Shield or two, especially when facing everyone's favorite undying zombie horde. Power Drain is the ultimate weapon against large groups of angry and armored Brutes. Gravity Lifts are the only way to reach the safe upper balconies and ambush-friendly ventilation ducts of the interior missions.
And guess what? Previously untested stuff like the Regenerator, Flare and Camouflage are even better. Looks like the team at Bungie knew what it was doing here after all.