It's not good on every jungler, but for on-hit based champions, it's certainly good. It's the best on-hit item in the entire game, with its cheap cost, high attack speed (the highest of any single item in the game), and 4% max health damage on-hit, again the best in the game. Low cost, the highest attack speed of any item in the game (the only other item with 50% is Nashor's Tooth and technically Dervish Blade, but that's not an SR item), and the best on-hit passive in the game, all for 2625 total gold, which isn't the best for on-hit items, but it certainly is cheap. Who did you try it on, might I ask? I would say that it's best on Warwick (if you plan to build tanky after your first 2 items), Nocturne (if you play to build tanky after the first item or 2), Shyvana (always), and Kindred (always). It's also amazing on Twitch jungle. Pretty much, for physical DPS that focuses on sustained damage with basic attacks over burst, get Bloodrazor. For physical damage burst or ability-based champions, get Warrior.