Island Hopping was successful. The U.S. was able to get close enough to Japan to launch a mainland invasion on Hiroshima and later Nagasaki which led to the Japanese surrender. However this campaign took long and was very costly.
On July 6, 1945 the U.S. Sixth Marine Division prepared for the expected mainland invasion of Japan. The atomic bomb was tested in New Mexico since it was the first one. Finally on August 6, 1945 they launched an atomic bomb over Hiroshima causing many civilians to die. This told the Japanese leaders to surrender or they would launch another bomb and since they didn't, three days later another atomic bomb was launched over Nagasaki then leading to the surrender of the Japanese.
Island Hopping was a turning point because if the Japanese had just taken away the U.S. fuel they could've possibly one the war. The reasons why is because the United States would not have enough fuel for all the attacks on the islands, this could have led to the Japanese capturing Hawaii becoming a threat to us. If this had happened the Island Hopping Campaign wouldn't have been possible. It's also considered a turning point because the president of the United States had to make a decision on whether to launch bombs where civilians lived, he took the decision to launch it and it costs many Japanese civilian lives, but if this hadn't happened it would have been more costly for the United States.
In this image we see Hiroshima after the bombing.