Ninja is literally the most valuable DPS in the game at the moment. Smoke Screen and Shadewalker are invaluable for allowing tanks to DPS harder in savage, Goad addresses the inevitable TP drain that all TP using classes run in to, and Trick Attack all but trivializes DPS checks with a 10% boost to everyone in the party. Between Trick attack and Shade Walker it actually provides more single target damage throughout the entire party compared to Monk and Black Mage. It's AOE also isn't terrible now that it was buffed, it's pretty average compared to the jobs.