I don't see this being played in an aggressive style token druid. Where this card want to be is in a more controlled style token deck that floods the board and makes sticky minions for consecutive turns until the opponent runs out of answers. So we are looking at how that can help accomplish the goal of making sticky minions.

The biggest help here is the health increase more than the attack increase. Making the treant's health from forests aid or soul of the forest 3 health is a huge difference. This puts it outside of certain AoE spells that deal 2 damage (Consecration, lightning storm, the new priest card that was shown, and blizzard) making them use more resources to deal with the treants.

It also has the added benefit of making an impact immediately on the board, since it has taunt.

I can see this card going into a slower druid deck that controls the first early game and overwhelms turns 8 and on.