Sniper's high individual damage is useful in the early-game, but other Monkeys do more DPT for less cost, namely the Dart Monkey Twins and Mortar Monkey. While a decent candidate for Try this!, and serviceable in newbie decks, other Monkeys simply do better than Sniper's minor one-shot strength. Its only redeemable factor is being a Common, which increases chances of drawing a Monkey card.
Unlike all other Commons, a Sniper Monkey can one-shot a Golden Bloon, even on Dark Castle.