180 munition for not reliably counter a lefh means it is totally suck.
I think it is reliable the overwhelming majority of the time, though when frantically waiting for the enemy unit to appear to click the ability on it, it's possible to misclick slightly to the side, causing a shell or two to miss.
If it was made to be more consistent, I think that would be fine as it wouldn't really buff it's function in any way.
If all shells landed closer to the targeted point, it wouldn't suddenly become a tank or blob killer since dodging it is extremely easy.
But no, it definitely doesn't "suck" -- it does it's job bretty darn well.