Is Axe's Battle Hunger a good skill for Jungle Axe?

Recently I have been getting into a discussion with my friend over Axe's Battle Hunger ability (his W), he is under the impression that the skill is awful and will not even touch the ability till level 22. He thinks due to Axe's low mana pool you are unable to use it efficiently early on when you need to cast other, more important spells. And that the damage it does is easily stopped by some semi-decent last hitting.

For an Axe who is in the jungle and comes out for ganks in the start of the game is Battle Hunger a viable skill at all? If not viable early game, when is it good to get over stats, and why?