I have the impression that Willy Junior wasn't all that much brighter than his dad. He did have sense enough to realize that Verdun was just a monstrously terrible battle, and tried to call it off, getting his wish several months later.
That being said, I cannot see him make the absolutely-same decisions that William made OTL. The Great War might be averted, but then again, recalling the militarism existing in Germany in particular as well as in Europe in general during that era, Willy might charge ahead somewhere else.