All in all, I would say that the German offensive was something of a forlorn hope in the Victorian sense in that it could do little more than demonstrate the Wehrmacht was still an entity to be regarded with caution. It made a certain amount of sense in tactical terms, but strategically it was a misstep. All the men and materiel devoted to the Ardennes offensive would have been much better used in the east to stem the Russian advance. Hitler, who was a firm believer in taking the offensive simply chose the wrong target. Strengthening the defensives in the west and limiting offensive operations there to counter attacks and probes while mustering forces for a major strike at the Russian Army might have been a better option. Certainly the men, tanks and other materiel lost in the west could not be replaced. All in all, inspite of some initial and spectacular success on the tactical level, the Ardennes offensive effectively left the back door open in the east and created a salient in the west which threatened to entrap the German forces which created it.
One sees, in fact, a certain similarity between the Ardennes offensive and Lee's invasion of Pennsylvania in 1863. Taking the offenisve and abandoning a strong defense along interior lines was I think a mistake in both cases.
Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.