Ummm no. It's 45% Elemental damage, so basically an extra Eidolon worth. However, burst bonus double dips into this so an on-element Full Burst will hurt a lot more than off element.
Also, 25% def isn't much, but you get 25% less damage with elemental advantage. I believe it's actually -25% Elemental damage, but since all enemies have 100% Elemental, that's effectively the same thing. I'd need further testing on that, I'd need to run against a bad element on purpose.