some of the things that annoy me most about the loose cannon:
1) some people are better at timing it to double donk than others, obviously, but there are so many places on maps that seem almost designed to make them easy by just tap spamming as kaidus said (for instance, gullywash choke to big door, roughly the length of the point on viaduct, mid to saw room entrance on snakewater, etc.)
2) the effect it has on ubers is so ridiculous, plus it's really arbitrary based on map/whether u get a double donk or not, plus it does just enough dmg to make it where a medic can't even choose whether to milk or not because no medic will milk that hard, PLUS you can't even reach the demo with hitscan like you can a pyro so it doesnt have the same level of counter
3) any weapon whose principle effect is to stall someone's movement is detrimental to fun a lot of the time
4) combined with the nerfs to stickies, demos who run the loose cannon are massively rewarded on damage stats. I have yet to determine how much this translates to a substantive difference in gameplay (ie if that free extra 2000 dmg is useful dmg). if it is, then the weapon is too much of an upgrade to pipes. if it isn't then demos who use it will be fellated without merit and elevated to better teams than they deserve because so many people look at stats to judge someone's skill whether they admit it or not