Well this is a pretty straight forward question, do you ever use it? I have admittidly not used it a single time -20% damage seems like alot to trade in for only 10 hit points.
Although it must be better early game, for instance at level one where you base attack is 5 and hit points is 10. But I rarely prepare it since there are other more important (in my eyes) choices for the space. And I NEVER use it lategame.