From BBC on this Day:

The mission became popularly known as the Dambusters raid, and was immortalized in a 1954 war film. It was one of the most famous air operations of World War II. Casualties for the raid were high.

Eight of the original 19 Lancaster bombers were damaged or shot down, and of the 133 aircrew, 53 were killed and three captured. On the ground, too, almost 1,300 people were killed, including 749 Ukrainian prisoners of war based in a camp just below the Eder dam.

The Möhne and Eder reservoirs poured about 330 million tons of water into the western Ruhr valley. The flood waters spread for about 50 miles (80km) from the source. The spectacular, daring nature of the raid was a significant boost to British morale. But militarily, it was a failure. The squadron failed to breach the Sorpe dam; and the disruption to the German war production was minimal. Water supply in the Ruhr valley was back to original levels six weeks later.

The aircrew, however, became famous as war heroes, and the leader of the raid, Wing Commander Guy Gibson, was awarded the Victoria Cross. He died less than 18 months later, shot down at the age of 26 in September 1944.

Actually many air raids hardly stopped German war production and many raids hit only the prisoners, because they usually were unable to hide in shelters. But the loss of material and airmen for the Americans and British was incredible.

As a finale note - the Dambuster theme from the movie, which is part of the British war culture:

More? documentary about the development of the special bomb and Wikipedia entry