This thing certainly looks tough, but then you notice that the incoming fire is knocking seven bells out of your shield, despite the hefty armour supposedly protecting you. Bit of a design oversight I'd say! It's also slow, making you particularly vulnerable to plasma balls from Jackals, or plasma grenades from Grunts. Another shortcoming is that you can't independently rotate the turret when driving, because motion is always towards where the gun is pointing. This makes strafing impossible, forcing you into more risky head-on motion. And the machine gun scatters bullets so widely, it's almost too painful for me to use.
All in all, this thing is so clumsy that I generally steer clear of it. However, I'll admit that the blast from the gun can be pretty satisfying, taking out Ghosts or Banshees in one big bang.