A real waste of German resources that could have been put to better use holding back the Red Army. Had the Germans actually reached Antwerp and held their flanks, little would have been accomplished aside from a lengthening of allied supply lines due to the loss of the major port city.
I have read or heard when Eisenhower heard the Germans attacked he was actually very pleased as you mention because this was last strategic reserve the Nazis had left.
This last major German offensive of WWII, I think more than anything else, reflected Hitler’s disposition as a warlord. Of course most of his senior commanders were skeptical of the offensive as resources were dangerously low for the Reich. However, Hitler loved to roll the dice, felt that fate was on his side, and more than anything else, hated playing on defense all of the time.
In the long run it would simply have resulted in the Soviets reaching the Rhine, instead of just the Elbe, but it's not like Hitler cared what happened after he was dead.