Honestly, it was far more handy in year 1. At that point, it's recharge rate was twice as fast to what it is now and there was a lot more emphasis on playing safe over speedy. Back when wiping in the nightfall resulted in returning to orbit and restarting, there was a lot more emphasis on cheese spots and playing super safe which is where the icebreaker really excels because you don't need to leave safety for ammo. Now, people are more focused on dps which is where the icebreaker is terrible. There is still use for the icebreaker but you have to think of it differently. You want a different weapon that can hold up reasonable dps. Whenever the breaker is full, pull it out and unload it, whether that is a boss or just random ads. Then switch off to your primary or heavy and let it recharge. To take full advantage of it, you just want to dump it as much as possible and don't just sit on it waiting to recharge.