It helps you load the yard while drawing you a couple of cards in most cases A two mana 2/2 that can tap for mana of any color is already a great card, and this has an activated ability with two really relevant uses
Since it can only be used once, you will have circumstances where you may activate a card's Exhaust ability, and then find yourself ten turns later forgetting if you've activated the ability or not
In most cases, the answer is no, which means free cards for you and a massive card gap by turn 4 or 5
You get great combat keywords in vigilance and first strike, an extra combat phase, and an additional main phase
This giant noble can snowball dangerously with +1/+1 counters in decks that create green creature tokens in large numbers and in decks that use cards like Doubling Season or Hardened Scales
However, you can be incredibly lucky, and you could come across a very rare card like Charizard VMax