"If you learn to use it, however, it can work fairly well." Screen Shot or it didn't happen.
The following problems that seems like everyone agrees on:
1) a single target attack
2) very clunky to actually hit mobs properly
3) interrupts an attack chain
4) actually drops the DPS of an acrobat
5) costs a minimum of 6 AP and maxis out at 18 AP
6) is unnecessarily required for Vault
It appears several things need to change.
The AP cost or untangling it from the chain need to happen, the same with Vault. It probably needs to be sped up. The hitbox for landing the blow needs to either expand or it should include multiple targets. If its staying a single target attack, it needs an extra effect on it like an auto-stun.