Now, from the start this card looks terrible right? One mana for one damage is pretty bad, but take this into consideration: how many direct damage spells do you think green has that doesn't deal damage to you or have a limitation? 10, maybe 20? Wrong. There are only three unrestricted direct damage spells in green, including this one (the others are Bee Sting and Unyaro Bee Sting). Considering that the other spells have a 1:2 damage:mana cost ratio, it can be said that this is the best direct damage spell in green with no downside. Want to activate your Carnage Wurm but your opponent can block all of your creatures? Here's a solution. Is that Aven Mindcensor stopping you from finding land? How about that Ball Lightning that's charging towards you? Finally, what if Ali from Cairo is making it so you can't win through combat? That's a lot of "what ifs", but I think it demonstrates that this card isn't as bad as people may think from the get-go.
Pros: One of green's few direct damage spells without a drawback
Cons: Only does one damage