Lasting from July to November of 1917 this battle (also known as the Battle of Passchendaele) cost nearly a Million lives on both sides of the conflict.
Among Allied critics the argument is made that the objectives were too limited (capture of some ridges controlling a supply line), premature in the face of United States Expeditionary Force deployment, the tactics limited and antiquated, and the price too costly in resources that could have been diverted to other fronts (the Battle of Caporetto for instance).
Among German critics it exposed Ludendorff as a commander of limited skill and little imagination and it was objectively a tactical loss.
Allied apologists claim it blunted German offensive capabilities in the critical year of 1917 and diverted German resources from the Eastern Front which eventually collapsed anyway due to the Russian Revolution.
German ones point out the Germans held long enough to ensure that collapse and the transfer of resources West to enable the Ludendorff Offensive of 1918 (which failed).
It is possible that The Great War could have come to an ultimate decision ending in Allied victory without United States intervention. The British blockade was just as stifling as it had been against Napoleon a century earlier and the German Army after the failure of a reinforced Ludendorff no more resolute than the French (among which there was spreading mutiny). What would likely not have happened is a settlement as punitive as the Treaty of Versailles which led, ultimately, to the ascendancy of Hitler and the Second World War.
So, lives wisely spent or not? Or are you with Chairman Mao who said when asked if the invention of fire had been good for the Chinese people- ‘Too soon to tell’?