The bombing of Hiroshima is one of the most controversial subjects of WWII. You don't have to look hard to find internet forums with heated arguments for and against it. Did it shorten the war and save lives? Did Japan deserve it? Was it necessary? Were there other options? I've already recommended Shockwave: Countdown to Hiroshima by Stephen Walker as excellent reading, and my personal feeling is that bringing the war to an abrupt halt saved many lives - especially American lives, but Japanese, too. I don't believe anything but a real-life demonstration would have convinced Japan's military government to surrender. Yet I also feel very sad that it had to come to that – that many innocent people had to die to demonstrate the futility of continued fighting.
I'd heard rave and almost reverential recommendations of this book and wondered if my thoughts would be changed by reading it. The text is mostly straightforward and seemingly neutral in its judgment; it reports that most Hiroshimans did not blame the US for the bomb, they just wanted to get on with their lives as best they could. It is not until the very end that it seems to take on an agenda, and while I found the initial part of the book fascinating and compelling, the follow-up chapter was disappointing. It isn't especially graphic or horrific in its account, but does portray what ordinary Japanese experienced, and made me feel extremely grateful that such weapons have not been used since 1945.
This is a worthwhile book for anyone interested in the subject to read. But I would urge you not to read with the intent to fortify your opinion either way - the book's focus is much too narrow for such - but to read it for the history and human experience it reports.