After the overwhelming victories in the Battle of France and the Allies being cut off from the main battle forces, the battle of Dunkirk was viewed as a victory. Although this was considered to be a defeat, the main concern was the evacuation of as many troops as possible. While the losses could not be compared, the main factor was the troops on the beaches made it out successfully.
German point of view
The German troops were confident they would win easily due to the French soldiers that were trapped on the French sea ports were cut off from any help coming in. The battle of Dunkirk resulted in a strategic advantage. Although it was a success of capturing and killing many allied troops, the main point of the invasion did not happen which involved capturing the harbor to invade the English coast.