If you use it in Multiplayer, try shooting while tapping the aim button again and again and it will fire faster. Do not use this strategy if an enemy is circling around you or trying to move around, but only during desperate measures do so.
When fully upgraded, it is a weaker and lighter Flak Cannon without quick firing speed and splash damage.
It is sometimes useless if your enemy has a high damage, high speed projectile weapon.
It is a good weapon in both single-player and Multiplayer when fully upgraded.