Rommel quickly noticed the difference in the troops working on the Atlantic Wall compared to the troops under his command in Africa. The Afrika Korps were well disciplined, top-notch German soldiers. The Italians, even though Rommel initially downplayed their effectiveness, turned out to be very good soldiers as well (as he later admitted). At the Atlantic Wall, Rommel found undisciplined younger and older German soldiers. They and their officers had little heart in their defensive preparations. As last posted, he had the foreign national troops to deal with also. It was quite an assortment of men, equipment, and defenses to get up to speed before the Allied invasions came.
Rommel had approximately 6 months to prepare. He did a fairly good job turning troops over to a fighting force and getting defenses improved (even with supply materials limited). Given 6 more months, D-day would have been much bloodier. Given say a year, the Allies might have got thrown back into the sea. Rommel knew the battle was won or lost on the beaches. Unfortunately for him, he did not have supreme control over France and lost the arguement to have the Panzers close to the beaches. Rommel saw what Allied air supremacy did to his men in Africa. France would be worse, and it was. Armored divisions never made it close enough to Allied beachheads to be effective. German men fought bravely, with heavy casualties. Movement was reduced to after dark and under cover with minimal advances…