Such as? Losing 1 million American soldiers?
The figure of 1 million wasn't backed by anything, it was practically pulled out of the air, there wasn't one consistent estimate shared among US officials, still it would of course have been a lot..
However it was known that Japan were in a state of near surrender, just not
unconditional surrender: US intelligence had been cracked messages of the Japanese instructing their ambassador in Moscow to work on peace negotiations with the allies, month before the bombing foreign Minister Shigenori Togo wired him saying "Unconditional surrender is the only obstacle to peace.."
In terms of conditions, keeping the emperor in place was suffice, they could've granted them that, let them have them if they want, who cares..
I think the US government were more preoccupied that the USSR were due to declare war on Japan of August 8th, creating the risk that the Japanese would surrender to the latter rather than the former, giving the Soviets occupier status of Japan. (Which of course would have been terrible).
Still, I don't see why the US government didn't at least tell the Japanese of their new offensive capability, then maybe dropping the bomb to prove they were not bluffing would have been more justified, with the other options clearly exhausted..
I'm also concerned by the fact that rather than bombing a more strategic location they went for a town that was pretty well preserved and not altered by conventional bombing in the way Tokyo was.
At best it was an extreme (possibly to much so) measure to stop the advance of Stalin's USSR, at worst it was a sick form of nuclear test that was the only one to show that the bomb "worked".
Then again, making judgements on the righteousness of historical events is pointless, I wouldn't change any of history, for it would be impossible to tell how things would be different as a result..