In a thread close to 400 comments long, I can almost be assured that no one will read this post.
From what I have learned about Truman's decision about dropping the Bombs on Japan was this: By 1945, WWII was about to end no matter what. Japan has very few natural resources to draw upon and were running out of any options other than surrender (or annihilation). Also Hitler had been stopped from advancing for over a full year, and scholars today agree that if the Bombs didn't drop, WWII would have ended all the same.
However, at the time, WWII was approaching a decade long struggle. Truman was new to the Presidency, and was also new to the detailed specifics of the War. The Manhattan project was reaching the testing stages as he assumed the Presidency. He was reported to have feared using the Bombs at all, when he was told of their devastating power. He couldn't have possibly imagined the actual power of the bombs, as no one person really can, nor their long term impact. American reports of the Bombs dropping were as such: 'America drops a bomb on Hiroshima.' 'America receives no word from the Japanese government.' 'America proceeds as planned to drop a bomb on Nagasaki.' But Japanese officials had not heard of the attack on Hiroshima because there was simply no way for communication to leave the area.
While I believe that the atomic bomb is too strong a weapon to use to murder any human being, I can understand why its use came into play given the circumstances. Unfortunately understanding the situation in no way relieves the reality of what the American government is responsible for. It is a particular tragedy that the cities were specifically targeted for being entirely of civilian population. And to relate the issue to your specific question of "Yes or no": there is no 'yes or no'. There are events that have happened in the past, and we must deal with them in the present. The answer in reality is yes. The bombs did indeed drop. The answer in morality is no, the bombs should not have been dropped. Hopefully this did something to answer your question.